Question

A semicircle had an area of 76.97 km squared. Find it's radius

Answer 1

`r = 7\ km`

Explanation:

The formula for the area of a circle is:

`A = \pi r^2`

Since we know that a semicircle is half of a circle, we can say the area is:

`A = (1)/(2)\pi r^2`

From here solve for r:

`76.97 = (1)/(2)\pi r^2\\153.94 = \pi r^2\\(153.94)/(\pi) = r^2\\r = \sqrt{(153.94)/(\pi)}\\r = 7`