Question

Verify the identity:

cos x(tan x - sec(-x))=sin x-1

Answer 1

Explanation:

cos x(tan x - sec(-x))

Converting to sines/cosines:

= cos x ( sinx/cosx - 1 / cos(-x))

= cos x (sinx/cosx - 1/cosx)

= cosx( (sinx - 1) )/ cos x)

= sinx - 1.