3.5: Double- & Half-Angle Identities

Question

Use a half angle or reduction formula to fill in the blanks in the identity below: =________ +_________  

Answer 1

cosx^2 + sin^2x = 1

cosx^2 = 1- sin^2x

cos2x = cos^2x - sin^2x

cos2x - cos^2x = -sin^2x

cosx^2 = 1+cos2x -cos^2x

2cos^2x = 1+cos2x

cos^2x = (1/2) + (cos2x)/2

cos^2(6x) = 1/2 +(1/2)cos12x

fill in the 3 blanks with 1/2, 1/2 and 12