I’m not sure if this is right but im guessing c.
A=pie×radius squared is the area formula of a circle. The circumference formula or a circle is C=pie×diameter. 615.75=(3.14)(radius) squared. Divide both sides by the 3.14. What ever 615.75 divided by 3.14 is-is radius squared. The square root is your radius. The radius is half the diameter, so double what you have right now as the radius to get the diameter. Now since C=pie×diameter, your circumference is your pie×your diameter. Whatever your answer is-is your circumference.
The perimeter of the equilateral triangle will be 76.2 in
<u>Explanation:</u>
Altitude of an equilateral triangle, H = 22 in
Perimeter, p = ?
Let a be the side of the triangle
We know:

Perimeter = 3a
P = 3 X 25.4 in
P = 76.2 in