The measurement around the crater is the circumference. We need to find the radius so we can find the area fo the crater.

Plug in values
79.5=2*(3.14)r
Multiply 2 and 3.14
79.5 = 6.28r
Divide both sides by 6.28
r approximately 12.66 miles
Area of a circle

Plug in values
A=(3.14)*12.66^2
Area = approximately
503.27 Sq Miles