Area of Triangles

1. The triangle shown below has an area of 12 units $^{2}$.

Find the missing length.

$x=$ ______ units

2. The triangle shown below has an area of 22 units ${ }^{2}$.

Find the missing length.

$x=$ ______ units

3. The triangle shown below has an area of 40 units $^{2}$.

Find the missing length.

$x=$ ______ units

4. The triangle shown below has an area of 10 units $^{2}$.

Find the missing length.

$x=$ ______ units