The law of cosines for TriangleRST can be set up as 52 = 72 + 32 – 2(7)(3)cos(S). What could be true about TriangleRST? Law of cosines: a2 = b2 + c2 – 2bccos(A) r = 5 and t = 7 r = 3 and t = 3 s = 7 and t = 5 s = 5 and t = 3