When you are given two sides of a right triangle, how do you find the third side?

Using the Pythagorean theorem which applies exclusively to right-angled (or right) triangles. The Pythagorean theorem states that in a right-angled triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides adjacent to the right angle. The hypotenuse is the side of the triangle opposite the right angle. Hence, using the figure as a guide: a^2+b^2=c^2 If you know any two of the three variables above (a, b, and c), the third can be easily calculated.

3 Ways to Find the Third Angle of a Triangle - wikiHow

3 Ways to Find the Third Angle of a Triangle - wikiHow

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