Question

Which best summarizes the Pythagorean Theorem?
The sum of the lengths of the legs of a right triangle equals the length of the hypotenuse.
The sum of the squares of the lengths of the legs of a right triangle equals the square of the length of the hypotenuse.
The length of the hypotenuse of a right triangle is greater than the sum of the lengths of the legs.
For any triangle, the sum of the squares of any two side lengths is equal to the square of the third side length.

Answer 1

"The sum of the squares of the lengths of the legs of a right triangle equals the square of the length of the hypotenuse."

This is the Pythagorean Theorem. The other choices are incorrect because they omit the squares, claim a false inequality, or apply to all triangles instead of only right triangles.