In a right-angled triangle ABC, angle C is a straight line, AB = 20, BC = 12, find AC

In △ ABC, the AB side is the hypotenuse, and the unknown AC side is the leg. We will use the Pythagorean theorem, according to which the sum of the squares of the legs is equal to the square of the hypotenuse:

AC ^ 2 + BC ^ 2 = AB ^ 2;

AC ^ 2 = AB ^ 2 – BC ^ 2;

AC ^ 2 = 20 ^ 2 – 12 ^ 2;

AC ^ 2 = 400 – 144;

AC ^ 2 = 256;

AC = √256;

AC = 16.

Answer: AC = 16.