12.5=3.14r^2

Solution for 12.5=3.14r^2 equation:

Simplifying
12.5 = 3.14r2

Solving
12.5 = 3.14r2

Solving for variable 'r'.

Move all terms containing r to the left, all other terms to the right.

Add '-3.14r2' to each side of the equation.
12.5 + -3.14r2 = 3.14r2 + -3.14r2

Combine like terms: 3.14r2 + -3.14r2 = 0.00
12.5 + -3.14r2 = 0.00

Add '-12.5' to each side of the equation.
12.5 + -12.5 + -3.14r2 = 0.00 + -12.5

Combine like terms: 12.5 + -12.5 = 0.0
0.0 + -3.14r2 = 0.00 + -12.5
-3.14r2 = 0.00 + -12.5

Combine like terms: 0.00 + -12.5 = -12.5
-3.14r2 = -12.5

Divide each side by '-3.14'.
r2 = 3.98089172

Simplifying
r2 = 3.98089172

Take the square root of each side:
r = {-1.995217211, 1.995217211}