36=3.14*r^2

Solution for 36=3.14*r^2 equation:

Simplifying
36 = 3.14r2

Solving
36 = 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.
36 + -3.14r2 = 3.14r2 + -3.14r2

Combine like terms: 3.14r2 + -3.14r2 = 0.00
36 + -3.14r2 = 0.00

Add '-36' to each side of the equation.
36 + -36 + -3.14r2 = 0.00 + -36

Combine like terms: 36 + -36 = 0
0 + -3.14r2 = 0.00 + -36
-3.14r2 = 0.00 + -36

Combine like terms: 0.00 + -36 = -36
-3.14r2 = -36

Divide each side by '-3.14'.
r2 = 11.46496815

Simplifying
r2 = 11.46496815

Take the square root of each side:
r = {-3.385995887, 3.385995887}