45-45-90 Triangles

Another special right triangle results when you cut a square in half using one of its diagonals.  Such a triangle is called a 45-45-90 triangle, because half each of 90^o angle is a 45^o angle:

Since the sides of a square are equal, we can label each leg of a 45-45-90 triangle as a.  Then the hypotenuse can be found by the Pythagorean Theorem:  ,  , .

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