ChallengeMedium ShareChallenge · Medium problemWhat is cos215∘−sin215∘\cos^2 15^\circ-\sin^2 15^\circcos215∘−sin215∘?A12\tfrac1221B22\tfrac{\sqrt2}{2}22C32\tfrac{\sqrt3}{2}23D111E3\sqrt33Check Show answer Walk through it step by step Practice more like this