How do you verify (1+sinx)/(1-sinx) - (1-sinx)/(1+sinx)=4tanxsecx1+sinx1sinx1sinx1+sinx=4tanxsecx?

1 Answer
Nov 1, 2015

See explanation.

Explanation:

[1]" "(1+sinx)/(1-sinx)-(1-sinx)/(1+sinx)[1] 1+sinx1sinx1sinx1+sinx

Combine the two terms by making them have the same denominator.

[2]" "=((1+sinx)/(1-sinx))((1+sinx)/(1+sinx))-((1-sinx)/(1+sinx))((1-sinx)/(1-sinx))[2] =(1+sinx1sinx)(1+sinx1+sinx)(1sinx1+sinx)(1sinx1sinx)

[3]" "=(1+2sinx+sin^2x)/(1-sin^2x)-(1-2sinx+sin^2x)/(1-sin^2x)[3] =1+2sinx+sin2x1sin2x12sinx+sin2x1sin2x

[4]" "=(1+2sinx+sin^2x-1+2sinx-sin^2x)/(1-sin^2x)[4] =1+2sinx+sin2x1+2sinxsin2x1sin2x

[5]" "=(4sinx)/(1-sin^2x)[5] =4sinx1sin2x

Pythagorean Identity: 1-sin^2theta=cos^2theta1sin2θ=cos2θ

[6]" "=(4sinx)/(cos^2x)[6] =4sinxcos2x

[7]" "=(4sinx)/((cosx)(cosx))[7] =4sinx(cosx)(cosx)

Quotient Identity: sintheta/costheta=tanthetasinθcosθ=tanθ

[8]" "=(4tanx)/(cosx)[8] =4tanxcosx

Reciprocal Identity: 1/costheta=sectheta1cosθ=secθ

[9]" "=4tanxsecx[9] =4tanxsecx

color(blue)("":.(1+sinx)/(1-sinx)-(1-sinx)/(1+sinx)=4tanxsecx)