Double Angle Identities

Write the trigonometric expression in terms of a single trigonometric function. 2tan 9x/ 1 − tan² 9x

If tanx = − 15/8  and  270° < α < 360° Find the exact value of cos(2x)

The formula for tan(2x) = 2tanx/1-tan²x

Write cos⁴x in terms of the first power of one or more cosine functions

Given cosx = − 2/3    π /2 < α < π Find sin(2x)

One of the formulas for cos(2x) = 2cos²x+1

Which of the following describes the relationship of sin(2x)?

If sinx=4/5 and 0º<x<90º Find the exact value of sin2x

Write 2(sin8xcos8x) in terms of a single trigonometry function.