Subtract from both sides of the equation.

Factor out of .

Factor out of .

Factor out of .

Rewrite as .

Since both terms are perfect squares, factor using the difference of squares formula, where and .

Remove unnecessary parentheses.

Divide each term in by .

Simplify .

Cancel the common factor of .

Cancel the common factor.

Rewrite the expression.

Cancel the common factor of .

Cancel the common factor.

Divide by .

Divide by .

Solve for p p=pr^2