Squares and square roots are related to triangles in that the Pythagorean theorem, which involves squares and square roots, can be used to find the length of the sides of a right triangle. The theorem states that in a right triangle, the square of the length of the hypotenuse is equal to the sum of the squares of the lengths of the other two sides. This relationship between squares and square roots allows for the calculation of unknown side lengths in a triangle when the lengths of the other sides are known.
