800=3.14r^2

Solution for 800=3.14r^2 equation:

Simplifying
800 = 3.14r2

Solving
800 = 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.
800 + -3.14r2 = 3.14r2 + -3.14r2

Combine like terms: 3.14r2 + -3.14r2 = 0.00
800 + -3.14r2 = 0.00

Add '-800' to each side of the equation.
800 + -800 + -3.14r2 = 0.00 + -800

Combine like terms: 800 + -800 = 0
0 + -3.14r2 = 0.00 + -800
-3.14r2 = 0.00 + -800

Combine like terms: 0.00 + -800 = -800
-3.14r2 = -800

Divide each side by '-3.14'.
r2 = 254.7770701

Simplifying
r2 = 254.7770701

Take the square root of each side:
r = {-15.96173769, 15.96173769}