the two calc formulas I guess we need to know but probably wont be on the test
power reducing formula for cos²(x) → 1/2(1+cos(2x))
power reducing formula for sin²(x) → 1/2(1-cos(2x))
power reducing formula for cos²(x) → 1/2(1+cos(2x))
power reducing formula for sin²(x) → 1/2(1-cos(2x))