How do you prove that cosx/(1-sinx) - 1/cosx = tanxcosx1sinx1cosx=tanx?

1 Answer
Apr 16, 2015

f(x) = cos x/(1 - sin x) - 1/cos x = [cos ^2 x - (1 - sin x)]/(cos x*(1 - sin x)f(x)=cosx1sinx1cosx=cos2x(1sinx)cosx(1sinx)

In the numerator of f(x),f(x), replace

cos^2 x = 1 - sin^2 xcos2x=1sin2x

Numerator = 1 - sin^2 x - 1 + sin x ==1sin2x1+sinx=

sin x*(1 - sin x)sinx(1sinx)

f(x) = (sin x*(1 - sin x))/(cos x*(1 - sin x))= sin x/cos x = tan x.f(x)=sinx(1sinx)cosx(1sinx)=sinxcosx=tanx.