1962.5=3.14r2

Solution for 1962.5=3.14r2 equation:

1962.5=3.14r^2

We move all terms to the left:

1962.5-(3.14r^2)=0

We get rid of parentheses

-3.14r^2+1962.5=0

a = -3.14; b = 0; c = +1962.5;
Δ = b2-4ac
Δ = 02-4·(-3.14)·1962.5
Δ = 24649
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{24649}=157$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-157}{2*-3.14}=\frac{-157}{-6.28}
=+25
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+157}{2*-3.14}=\frac{157}{-6.28}
=-25
$