x = one of the legs

√1215 = other leg

4x = hypotenuse {hypotenuse is four times the length of one of the legs}

a² + b² = c² {Pythagorean Theorem}

a and b are the legs and c is the hypotenuse

x² + (√1215)² = (4x)² {substituted into Pythagorean Theorem}

x² + 1215 = 16x² {evaluated exponents}

1215 = 15x² {subtracted x² from each side}

x² = 81 {divided each side by 15}

x = 9 {took square root of each side}

4x = 36 {substituted 9, in for x, into 4x}

**one leg is 9
**

hypotenuse is 36*- Algebra House
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