What is the perimeter of the triangle?

Triangle HIJ is shown below.  What is the perimeter of the triangle?

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Find the missing side, HJ, by using the pythagorean theorem.

Pythagorean Theorem
a² + b² = c²  {the sum of the squares of the legs is equal to the square of the hypotenuse}
12² + b² = 13²  {substituted sides into pythagorean theorem}
144 + b² = 169  {evaluated exponents}
b² = 25  {subtracted 144 from each side}
b = 5  {took square root of each side}

The sides of the triangle are 5, 12, and 13.

Perimeter = 5 + 12 + 13 = 30 cm  {added sides of triangle}

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