Question

A semicircle has an area of 76.97 km² . Find its radius

Answer 1

Area of a semicircle = 1/2 πr² 

 1/2 πr²  = 76.97

Multiply both sides by 2:
πr² = 153.94

Divide both sides by π:
r² = 49

Square root both sides:
r=√49

r = 7

Answer: r = 7

Answer 2

Hello!

We first have to make the semicircle a whole circle

A semicircle is half a circle so we multiply the area by 2

76.97 * 2 = 153.94

Now we use the equation to find the radius when given the area which is

$r= \sqrt{ \frac{A}{ \pi} }$

r is radius
A is area

Put in the values we know

$r= \sqrt{ \frac{153.94}{ \pi }}$

Divide 153.94 by pi

$r = \sqrt{49}$

Take the square root

r = 7

The answer is 7km

Hope this helps!