1. The Pythagorean theorem is a fundamental relation in geometry among the three sides of a right triangle. 2. It states that in a right triangle, the square of the hypotenuse ($c$) is equal to the sum of the squares of the other two sides ($a$ and $b$): $$c^2 = a^2 + b^2$$ 3. This theorem is used to find the length of one side when the lengths of the other two sides are known. Answer: Yes.