72.3456=3.14*r*r

Solution for 72.3456=3.14*r*r equation:

Simplifying
72.3456 = 3.14r * r

Multiply r * r
72.3456 = 3.14r2

Solving
72.3456 = 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.
72.3456 + -3.14r2 = 3.14r2 + -3.14r2

Combine like terms: 3.14r2 + -3.14r2 = 0.00
72.3456 + -3.14r2 = 0.00

Add '-72.3456' to each side of the equation.
72.3456 + -72.3456 + -3.14r2 = 0.00 + -72.3456

Combine like terms: 72.3456 + -72.3456 = 0.0000
0.0000 + -3.14r2 = 0.00 + -72.3456
-3.14r2 = 0.00 + -72.3456

Combine like terms: 0.00 + -72.3456 = -72.3456
-3.14r2 = -72.3456

Divide each side by '-3.14'.
r2 = 23.04

Simplifying
r2 = 23.04

Take the square root of each side:
r = {-4.8, 4.8}