Write the word or phrase that best completes each statement
Write the word or phrase that best completes each statement or answer Establish the identity. (sin x) (tan x cos x - cot x cos x) = 1 - 2 cos^2 x
Solution
12. sinx(tanx cos x - cotx cosx) =1-2cos2x
Starting with the left side
sinx(tanx cos x- cotx cos x)
using tanx =sinx/cos x and cot x=cos x/sin x
sinx(cos x(sin x/cos x)- (cos x/sin x)cosx)
sinx(sinx - cos2x/sinx)
Distributing sinx
sin2x - cos2x
1-cos2x - cos2x = 1-2cos2x which is equal to right side
