To answer this question we will need to use the formula, A = π r2. π also known as 3.14. Dividing both sides of this equation by π gives
A/π = r2
and hence if you know A, divide it by π and then take the square root to find r.
So, 78.5/3.14 and r2/3.14 which gives us 25=r2. Now do the square root. √25=r2 which is 5=r. So your final answer is Radius=5.
