Please help me to answer this question, not even sure where to begin. Thanks in advance

4. Use Pappus' Variation to prove the Pythagorean Theorem. The first thing you will have to do 1s decide how to apply Pappus' result. Start with a right angle triangle with right angle at C, and put squares on the shorter sides. You will have to prove that the parallelogram on the hypotenuse, as described in Pappus' Theorem, is in fact a square