13. If the lengths a, b, and c of the sides of a right triangle are positive integers, with a2 + b2 = c2, then they form what is called a Pythagorean triple. The triple is normally written as (a,b,c). For example, (3,4,5) and (5,12,13) are well-known Pythagorean triples. (a) Show that (6,8,10) is a Pythagorean triple. (b) Show that if (a,b,c) is a Pythagorean triple then so is (ka,kb,kc) for any integer k >0. How would you interpret this geometrically?