Circumference and Area of a Circle

1. Radius \(=9 cm\)

Diameter \(=18 cm\)

2. Radius \(=4.2 cm\)

Diameter \(=8.4 cm\)

3. \(=16\) units

4. \(=8\) units

5. Radius \(=6.5 cm\)

Diameter \(=13 cm\)

6. Radius \(=16 cm\)

Diameter \(=32 cm\)

7.  \(=4\) units

1. A circle has a circumference of \(113.04\) units.

What is the diameter of the circle?

_______ units

2. A circle has a circumference of \(452.16\) units.

What is the radius of the circle?

_______ units

3. What is the circumference of the following circle?

_______ units

4. Suppose the diameter of a circle is \(16\) units. What is its circumference?

_______ units

1. The answer

The diameter is approximately 36 units.

2. The answer

The radius is approximately 72 units.

3. \(\approx 6.28\) units

4. \(\approx 50.24\) units

1. Find the area of a circle with a circumference of \(31.4\) units.

_________ units \(^{2}\)

2. What is the area of the following circle?

Either enter an exact answer in terms of \(\pi\) or use \(3.14\) for \(\pi\) and enter your answer as a decimal.

_________ units \(^{2}\)

Either enter an exact answer in terms of \(\pi\) or use \(3.14\) for \(\pi\) and enter your answer as a decimal.

_________ units \(^{2}\)

4. Find the area of a circle with a circumference of \(6.28\) units.

_________ units \(^{2}\)

5. Find the area of a circle with a radius of 2.

Either enter an exact answer in terms of \(\pi\) or use \(3.14\) for \(\pi\) and enter your answer as a decimal.

_________ units \(^{2}\)

6. Find the area of a circle with a diameter of 4.

Either enter an exact answer in terms of \(\pi\) or use \(3.14\) for \(\pi\) and enter your answer as a decimal.

_________ units \(^{2}\)

7.  Find the area of a circle with a circumference of \(18.84\) units.

_________ units \(^{2}\)

1. \(A \approx 25 \pi\)

\(A \approx 78.5 unit ^{2}\)

2. \(A=16 \pi\)

3. \(A=25 \pi\)

4. \(A \approx 1 \pi\)

\(A \approx 3.14\) unit \(^{2}\)

5. \(A=4 \pi\)

6. \(A=4 \pi\)

7.  \(A \approx 9 \pi\)

\(A \approx 28.26\) unit \(^{2}\)

1. 

Find the arc length of the semicircle.

Either enter an exact answer in terms of \(\pi\) or use \(3.14\) for \(\pi\) and enter your answer as a decimal.

________ units

2. 

Find the arc length of the partial circle.

Either enter an exact answer in terms of \(\pi\) or use \(3.14\) for \(\pi\) and enter your answer as a decimal.

________ units

________ units

4. 

Find the arc length of the semicircle.

Either enter an exact answer in terms of \(\pi\) or use \(3.14\) for \(\pi\) and enter your answer as a decimal. units

________ units

1. The answer

The arc length of the semicircle is \(4 \pi\) units.

(Note that we could also multiply 4 by \(3.14\) to get \(12.56\) units.)

2. The answer

The arc length of the partial circle is \(3.5 \pi\) units.

(Note that we could also multiply \(3.5\) by \(3.14\) to get \(10.99\) units.)

3. The answer

The arc length of the partial circle is \(\frac{1}{2} \pi\) units.

(Note that we could also multiply \(\frac{1}{2}\) by \(3.14\) to get \(1.57\) units.)

4. The answer

The arc length of the semicircle is \(6 \pi\) units.

(Note that we could also multiply 6 by \(3.14\) to get \(18.84\) units.)

1. 

Find the area of the shape.

Either enter an exact answer in terms of \(\pi\) or use \(3.14\) for \(\pi\) and enter your answer as a decimal.

________ units \(^{2}\)

2. 

Find the area of the semicircle.

Either enter an exact answer in terms of \(\pi\) or use \(3.14\) for \(\pi\) and enter your answer as a decimal.

________ units \(^{2}\)

3. 

Find the area of the semicircle.
Either enter an exact answer in terms of \(\pi\) or use \(3.14\) for \(\pi\) and enter your answer as a decimal.

________ units \(^{2}\)

4. 

Find the area of the shape.
Either enter an exact answer in terms of \(\pi\) or use \(3.14\) for \(\pi\) and enter your answer as a decimal.

________ units \(^{2}\)

1. The answer

The area of the shape is \(3 \pi\) units \(^{2}\).

(Note that we could also multiply 3 by \(3.14\) to get \(9.42\) units \(^{2}\).)

2. The answer

The area of the semicircle is \(12.5 \pi\) units \(^{2}\).

(Note that we could also multiply \(12.5\) by \(3.14\) to get \(39.25\) units \(^{2}\).)

3. The answer

The area of the semicircle is \(4.5 \pi\) units \(^{2}\).

(Note that we could also multiply \(4.5\) by \(3.14\) to get \(14.13\) units \(^{2}\).)

4. The answer

The area of the shape is \(12 \pi\) units \(^{2}\).

(Note that we could also multiply 12 by \(3.14\) to get \(37.68\) units \(^{2}\).)