In geometry, a theorem stating that in a right triangle, the square of the hypotenuse (the longest side) is equal to the sum of the squares of the other two sides (legs). If the hypotenuse is c units long and the lengths of the legs are a and b, then c2 = a2 + b2.
The theorem provides a way of calculating the length of any side of a right triangle if the lengths of the other to sides are known. It is also used to determine certain trigonometrical relationships such as sin2 q + cos2 q = 1.
Let a = 4 cm, b = 3 cm, and c = 5 cm
Using the Pythagorean Theorem,
c2 = a2 + b2
52 = 42 + 32
25 = 16 + 9
25 = 25