72=3.14r^2

Solution for 72=3.14r^2 equation:

Simplifying
72 = 3.14r2

Solving
72 = 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.
72 + -3.14r2 = 3.14r2 + -3.14r2

Combine like terms: 3.14r2 + -3.14r2 = 0.00
72 + -3.14r2 = 0.00

Add '-72' to each side of the equation.
72 + -72 + -3.14r2 = 0.00 + -72

Combine like terms: 72 + -72 = 0
0 + -3.14r2 = 0.00 + -72
-3.14r2 = 0.00 + -72

Combine like terms: 0.00 + -72 = -72
-3.14r2 = -72

Divide each side by '-3.14'.
r2 = 22.92993631

Simplifying
r2 = 22.92993631

Take the square root of each side:
r = {-4.788521307, 4.788521307}