Topic	Name	Description
Course Syllabus	Course Syllabus

1.1: Language and Notation	The Language and Notation of Basic Geometry	Watch this video. Make sure you understand the definitions for line, line segment, ray, midpoint, collinear, and planar.
	Lines, Line Segments, and Rays	This video discusses the differences between geometric objects that may appear to be similar: lines, line segments, and rays.

1.2: The Distance between Two Points	The Distance between Two Points	Read this article and watch the videos. Pay attention to the sections on the ruler postulate and the segment addition postulate. These two postulates help us perform certain measurements. The videos give examples. Read the examples near the end of the page closely to see step-by-step solutions. Then, complete review questions 1, 2, 6, 7, 9, 10, 11, 16, and 17 and check your answers.

1.3: Midpoints and Segment Bisectors	Midpoints and Segment Bisectors	Read this article and watch the video to learn about these concepts. Pay close attention to the midpoint formula, since we use this formula to determine the midpoint of a segment. Then, complete guided practice questions 1–3 and check your answers.

1.4: Measuring Angles	Angles	First, watch this video to learn the vocabulary of angles.
	Measuring Angles	Once you feel comfortable with the vocabulary we use to describe angles, watch these videos to learn how to use a protractor, the tool we use to measure angles accurately. The videos also explain the units we use to define angles.

1.5: Congruent Angles and Angle Bisectors	Congruent Angles and Angle Bisectors	Read this article and watch the videos. Pay attention to the section on investigation, which explains the step-by-step method for constructing an angle bisector. Carefully read the examples. Then, complete practice questions 1, 5, 11, and 12 and check your answers.

1.6: Acute, Obtuse, and Right Angles	Acute, Right, and Obtuse Angles	Watch these videos to learn about ways to classify angles based on their degree.

1.7: Complementary and Supplementary Angles	Complementary and Supplementary Angles	Watch these videos. Pay close attention to the definition of complementary and supplementary used to describe sets of angles.
	Practice with Complementary and Supplementary Angles	Then, complete this assessment and check your answers.

1.8: Linear Pairs	Linear Pairs	Read this article and watch the videos to learn about linear pairs, adjacent angles, and angles that form a linear pair. Pay attention to the examples of how to measure angles and identify linear pairs. Then, complete review questions 6, 7, 12, and 13 and check your answers.

1.9: Vertical Angles	Vertical Angles	Watch this video to learn about vertical angles and how they relate to each other.
	Equations with Vertical Angles	Then, watch this video for more advanced examples that use algebra.
	Practice Solving Problems with Vertical Angles	Then, complete this assessment, which combines what you know about vertical angles with basic algebra to solve problems.

1.10: Polygon Classification	Classifying Polygons	Read this article. The table lists the common types of polygons we will encounter in geometry.

2.1: Parallel, Perpendicular, and Skew Lines	Identifying Parallel and Perpendicular Lines	Watch this video to learn how to identify these types of lines.

2.2: Angles and Transversals	Angles, Parallel Lines, and Transversals	Read this article and watch the video. These materials use language we will explore in later sections, but you should understand how to calculate the angle of a transversal. Pay close attention to how to calculate an unknown angle on a transversal line.

2.3: Corresponding Angles	Corresponding Angles	Read this article and watch the videos. The corresponding angle postulate states that corresponding angles have approximately the same degree measurement. Watch the videos to see examples of how to calculate corresponding angles and their measurements. Carefully read examples 1–3. Then, complete review questions 2, 3, 4, 11, 12, 13, 14, and 15 and check your answers.

2.4: Alternate Interior Angles	Alternate Interior Angles	Read this article and watch the videos. Pay attention to the alternate interior angles theorem, which states that alternate interior angles are congruent. Do not focus on the proof, but pay attention to the example on measuring angles. Then, complete review questions 1, 2, 6, 7, and 8 and check your answers.

2.5: Alternate Exterior Angles	Alternate Exterior Angles	Read this article and watch the videos. Pay attention to the alternate exterior angles theorem. As in the last section, do not focus on the proofs. Rather, focus on the examples that demonstrate how to recognize alternate exterior angles, measure angles, and apply these concepts to the real world. Then, complete review questions 1, 2, 3, 4, 13, 14, and 15 and check your answers.

2.6: Same Side Interior Angles	Same Side Interior Angles	Read this article and watch the videos. Pay attention to the same side interior angle theorem. Read the examples on recognizing same side interior angles and measuring angles closely. Then, complete review questions 1–5 and check your answers.

2.7: Distance Formula in the Coordinate Plane	Using the Distance Formula	Watch this video on how to use the distance formula to find the distance between two points and a few examples of how to do it.
	Practice Using the Distance Formula	After you watch the video, complete this assessment and check your answers.

3.1: Triangle Classification	Triangle Classification	Read this article and watch the videos to learn how to classify triangles based on their angles and sides. Pay attention to the list of different types of triangles. It may be helpful to make a list of these different classifications of triangles and their characteristics.

3.2: Triangle Sum Theorem	Using the Triangle Sum Theorem	Watch this video to see why the triangle sum theorem works.
	Practice Using the Exterior Angle Theorem	Then, complete this assessment and check your answers.

3.3: Exterior Angle Theorem	Using the Exterior Angle Theorem	Watch this video to see an example of how to use the exterior angle theorem.
	Practice Using the Exterior Angle Theorem	Then, complete this assessment and check your answers.

3.4: Congruent Figures	Congruent Figures	Read this article and watch the video. Pay attention to the steps you need to take to determine if two figures are congruent.

3.5: Congruent Triangles and SSS	Congruent Triangles and the SSS Postulate	Watch this video to learn how to use the SSS postulate to determine if two triangles are congruent.

3.6: Other Triangle Congruence Postulates	The SAS, ASA, and AAS Postulates	Watch this video for definitions of these postulates and examples of how to use them.

3.7: Calculating Congruent Triangles	Congruent Triangles	Watch this video for examples of how to use different postulates to determine the congruence between triangles.
	Practice with Congruent Triangles	Then, complete this assessment and check your answers.
	Practice with Angles in Congruent Triangles	Complete this assessment and check your answers.

3.8: Isosceles Triangles	Isosceles Triangles	Read this article and watch the videos. Pay attention to the terminology that it introduces about isosceles triangles. The base angle theorem states that the base angles of an isosceles triangle must be congruent. Do not focus on the proof. Pay attention to the examples of how to recognize congruent angles, measure vertex angles, and measure base angles. Then, complete review questions 1–5 and check your answers.

3.9: Equilateral Triangles	Equilateral Triangles	Read this article and watch the videos. Pay attention to the equilateral triangle theorem and examples 3–5. Then, complete review questions 1–4 and check your answers.

4.1: Midsegment Theorem	Midsegment Theorem	Read this article and watch the videos. Pay attention to the definitions of midsegment, the midsegment theorem, and how to calculate the length of a midsegment. Review examples 1–5 to see how to use the midsegment theorem to solve for unknown quantities in triangles. Then, complete review questions 5, 6, 9, 10, and 16, and check your answers.

4.2: Perpendicular Bisectors	Perpendicular Bisectors	Read this article and watch the videos. Pay close attention to the definition of a perpendicular bisector and the perpendicular bisector theorem, which tells us how to make a triangle out of a line segment and a perpendicular bisector. Read examples 1–5. Then, complete review questions 1–3 and check your answers.

4.3: Angle Bisectors	Angle Bisectors	Read this article and watch the videos. Pay attention to the angle bisector theorem, which states that any point on an angle bisector is equidistant to both sides of the angle. This allows us to create two identical triangles on either side of the angle bisector. Closely read examples 1–3. Then, complete review questions 1–3 and check your answers.

4.4: Medians	Triangle Medians and Centroids	Watch this video to learn about this property of triangles.
	Using Medians and Centroids to Solve Unknown Quantities	Watch this video to see an example of how to use medians to solve for unknown quantities in a triangle.

4.5: Altitudes	Altitudes	Read this article and watch the videos. Pay attention to the figures that show how to draw altitudes for acute, right, and obtuse triangles. Carefully read examples 1–5, which describe how to draw altitudes for different types of triangles.

4.6: Triangle Inequality Theorem	Triangle Inequality Theorem	Read this article and watch the videos. Focus on the examples of solving for unknown length and making conclusions about lengths of legs. Pay attention to how to determine whether a given set of lengths will form a triangle.
	Practice Using the Triangle Inequality Theorem	Then, complete this assessment and check your answers.

5.1: Sum of Interior Angles of a Polygon	Quadrilaterals, Polygons, and Transformations	Read this article, which reviews types of quadrilaterals and how to calculate the sum of polygon angles.
	Sum of Interior Angles of a Polygon	Now we are ready to explore the interior angles of a polygon in more detail. Watch this video for examples of how to determine the sum of the interior angles in a polygon.

5.2: Sum of Exterior Angles of a Convex Polygon	Sum of Exterior Angles of a Convex Polygon	Watch this video to learn how to perform this calculation and to see examples.
	Practice Adding Angles of a Polygon	Then, complete this assessment, which includes the sum of exterior angles of a polygon and the sum of interior angles of a polygon.

5.3: Parallelograms	Parallelograms	Read this article and watch the videos, which review the structure and properties of parallelograms. Pay attention to the list of theorems that pertain to parallelograms. These theorems are useful when solving for unknown side lengths or angles. Closely read the sections on measuring angles and solving for unknown values. Be sure to read examples 1–3. Then, complete review questions 1, 4, 5, 16, 17, 18, and 19 and check your answers.
	Classifying Parallelograms	We can classify different types of parallelograms based on their properties. Read this article and watch the video. Pay attention to the definitions for rectangle, rhombus, and square. Then, complete review questions 4–15 and check your answers.

5.4: Trapezoids	Trapezoids	Read this article and watch the video. Pay attention to the special form of the midsegment theorem as it applies to trapezoids. Closely read examples 1–5. Then, complete review questions 2, 3, and 8 and check your answers.

5.5: Kites	Kites	Read this article and watch the two embedded videos which describe the properties of kites and shows various examples. Pay attention to the examples on measuring angles, using the Pythagorean theorem, and finding the missing angle. Closely read examples 1–3. After you have reviewed the material, complete review questions 1, 2, 7, and 8 and check your answers.

5.6: Coordinate Geometry	Quadrilaterals	Watch these two videos on quadrilaterals and their properties.
	Practice with Quadrilaterals	Then, complete this assessment to review your knowledge of quadrilaterals and check your answers.

6.1: Similar Polygons	Similar Triangles	First, watch this video, which describes the meaning of similarity and applies its definition to triangles, the simplest polygon.
	Similar Polygons and Scale Factors	Next, read this article and watch the videos, which also define similarity for polygons. The first video offers an example of using similarity to solve for unknown values in a polygon. Closely read example 1. Then, complete review questions 14–18 and check your answers.

6.2: Similarity Postulates	Similarity Postulates	Watch this video to learn how to apply similarity postulates to triangles.

6.3: Angle-Angle Similarity and Indirect Measurement	Angle-Angle Similarity Postulate	Read this article and watch the videos, which define AA similarity. Examples 1–5 show how to apply the AA similarity postulate to solve for unknowns in a triangle. Then, complete review questions 6, 7, 8 and 10 and check your answers.

6.4: Side-Side-Side and Side-Angle-Side Similarity	Side-Side-Side Triangle Similarity	Read this article and watch the four embedded videos. Pay attention to the Side-Side-Side (SSS) Similarity Theorem and the examples of determining if two triangles are similar and solving for unknown values. After you have reviewed the material, complete review questions 11–16 and check your answers.
	Side-Angle-Side Triangle Similarity	Next, read this article and watch the embedded video. Pay attention to the Side-Angle-Side (SAS) criterion for similarity and Examples 1–3, which explain how to apply this criterion to solve for unknown values. After you have reviewed the material, complete review questions 5–10 and check your answers.

6.5: Triangle Proportionality, Parallel Lines and Transversals	Solving Similar Triangles	Watch this video to see examples of problems where the similarity criteria are used to determine side lengths and angles of triangles.
	Practice Solving Similar Triangles Part I	After you have watched the video, complete these assessments to test what you have learned and check your answers.
	Practice Solving Similar Triangles Part II	Complete this second set of assessments and check your answers.

7.1: The Pythagorean Theorem	The Pythagorean Theorem	Watch this introductory video.
	Using the Pythagorean Theorem	Watch this video on how to use the Pythagorean theorem to solve for the length of an unknown side of a triangle.
	Practice Using the Pythagorean Theorem	Then, complete these practice problems and check your answers.

7.2: 45-45-90 Triangles	45-45-90 Right Triangles	Read this article and watch the videos to learn about the special properties of isosceles triangles. Pay attention to the examples of finding the length of missing side and solving for unknowns. The article also shows how we can divide squares into two isosceles triangles and then use our knowledge of these triangles to solve for an unknown. Then, complete review questions 9–12 and check your answers.

7.3: 30-60-90 Right Triangles	30-60-90 Right Triangles	Read this article and watch the videos. Pay attention to the 30-60-90 theorem, which gives the ratio needed to solve for an unknown side of this type of triangle. Then, complete review questions 5–8 and check your answers.

7.4: Sine, Cosine, and Tangent	Trigonometry	Read this page and watch the video. This gives a good overview of the three main trigonometric functions: sine, cosine, and tangent. It may be helpful to write the definitions down for yourself to keep track of them.
	Practice Trigonometric Ratios in Right Triangles	Then, take this assessment and check your answers.

7.5: Trigonometric Ratios with a Calculator	Using a Calculator for Trigonometric Ratios	Read this article and watch the videos to learn how to input trigonometric functions into your calculator. Then, complete review questions 1–3 and check your work to make sure you are able to use your calculator correctly.

8.1: Language and Notation of a Circle	Circle Language and Notation	Watch this video to become familiar with the terms we will use in this unit.

8.2: Tangent Lines	Tangent Lines	Read this article and watch the videos to learn about the tangent line theorem, which defines tangent lines, and the two tangents theorem, which we use to solve for unknown lengths of line segments. Read examples 1–5 closely to see how to draw tangent lines and how we can use tangent lines to solve for unknown quantities. Then, complete review questions 1, 2, 4, and 5 and check your answers.

8.3: Arcs of Circles	Arcs	Watch these videos, which introduce the idea of arcs in circles and give examples of how to determine the angle of a given arc.
	Practice Measuring Arcs	Then, complete this assessment and check your answers.

8.4: Inscribed Angles	Value of Inscribed Angles and Polygons	Read this brief article, which gives an overview of what inscribed angles are and how to identify them. Watch the video to see how to use your knowledge of triangles to determine the value of inscribed angles.
	Practice Inscribed Angles and Polygons	Then, complete this assessment and check your answers.

8.5: Angles of Chords, Secants, and Tangents	Chords in Circles	Read this article and watch the video. Pay attention to the examples of how to determine the lengths of chords and their angles. It may help to write down the four chord theorems to help you keep track of them as you work through the problems.
	Angles of Chords, Secants, and Tangents	Once you feel comfortable with the definition of chords and their theorems, read this article which details several ways we can calculate the angles formed by chords. Since this page has so much information, read slowly and take time to work through each example. It may be helpful to write down the many theorems to make sure you understand them. Then, complete review questions 1–10 and check your answers.

9.1: Perimeter and Area Basics	Perimeter and Area Basics	Watch this video to learn how mathematicians talk about these concepts.

9.2: Area of Triangles	Area and Perimeter of a Triangle	Read this article and watch the videos. Pay attention to the formula for the area of a triangle, including the special case of right triangles. Note that we use the Pythagorean theorem to calculate the perimeter of a triangle. Then, complete review questions 1–5 and check your answers.

9.3: Area and Perimeter of Rectangles and Squares	Area and Perimeter of a Rectangle	Read this article and watch the three embedded videos, which discuss the formulas we use to calculate the area and perimeter of rectangles and squares. After you have reviewed the material, complete review questions 1–6 and check your answers.

9.4: Area of a Parallelogram	Area of a Parallelogram	Read this article and watch the videos. Pay attention to how to "rearrange" a parallelogram into rectangles before calculating its area. Then, complete review questions 1, 2, 6, 7, 13, and 14 and check your answers.

9.5: Area and Perimeter of Trapezoids	Area and Perimeter of Trapezoids	Read this article and watch the two embedded videos, which highlight the formulas we use to calculate the area and perimeter of a trapezoid. After you have reviewed the material, complete review questions 1–5 and check your answers.

9.6: Area and Perimeter of Rhombuses and Kites	Area and Perimeter of Rhombuses and Kites	Read this article and watch the video which highlight the formulas we use to calculate the area and perimeter of rhombuses and kites. Then, complete review questions 2, 3, 4, 12, 13, 14, and 15 and check your answers.

9.7: Area and Perimeter of Similar Polygons	Area and Perimeter of Similar Polygons	Read this article and watch the video. These highlight the formulas we use to calculate the area and perimeter of similar polygons. Perimeters and areas of similar polygons are proportional.

9.8: Circumference	Circumference Review	Read this article, which explains the circumference formula and gives examples for calculating circumference. Then, complete the practice questions and check your answers.

9.9: Arc Length	Arc Length	Read this article and watch the videos. Note the arc length formula. Pay attention to the examples on measuring arc length, finding the radius, and measuring the central angle. Then, complete review questions 1, 5, and 8 and check your answers.

9.10: Area of a Circle	Area of a Circle	Watch this video, which introduces the formula for the area of a circle and an example of using this formula.
	Practice Calculating the Area of a Circle	Then, take this assessment and check your answers.

9.11: Area of Composite Shapes	Perimeter and Area of a Non-Standard Polygon	Watch this video to see how we can use what we learned about standard polygons to develop methods for determining the area and perimeter of a composite shape.

10.1: Polyhedrons	Polyhedrons	Read this article and watch the video which define different common types of polyhedrons. These also cover Euler's theorem, which defines the number of faces and vertices in a given polyhedron.
	Representing Solids	Read this article, which explains how three-dimensional solids are represented on paper and how we can map three-dimensional solids to two dimensions.

10.2: Prisms	Prisms	Read this article and watch the videos. Focus on the definitions for surface area and volume in the text. Carefully read the examples of finding surface area and volume. Then, complete review questions 9–12 and check your answers.

10.3 Cylinders	Cylinders	Read this article and watch the videos. Make note of the formulas for the surface area of a right cylinder and the volume of a cylinder. Then, complete review questions 3–6 and check your answers.

10.4: Pyramids	Pyramids	Read this article and watch the video. Note the formulas for surface area and volume of pyramids. Then, complete review questions 9–12 and check your answers.

10.5: Cones	Cones	Read this article and watch the videos. Pay attention to the formulas for surface area and volume. Then, complete review questions 1–3 and check your answers.

10.6: Spheres	Spheres	Read this article and watch the video. Focus on the formulas for surface area and volume. Then, complete review questions 4, 5, 10, 12, and 13 and check your answers.

10.7: Composite Solids	Composite Solids	Read this article and watch the video. Focus on the examples of how we can break composite solids down into standard shapes.

Course Feedback Survey	Course Feedback Survey