What is cot theta + tantheta*sectheta cotθ+tanθsecθ in terms of sintheta sinθ?

1 Answer
Jan 27, 2016

((1-sin^2theta)^(3/2) +sin^2theta)/(sintheta(1-sin^2theta)(1sin2θ)32+sin2θsinθ(1sin2θ)

Explanation:

You need to use the facts that cot theta = 1/tan theta cotθ=1tanθ and that tan theta = sin theta/cos thetatanθ=sinθcosθ

Then
cot theta +tan theta * sec theta = cos theta/sin theta + sin theta / cos theta * 1/cos thetacotθ+tanθsecθ=cosθsinθ+sinθcosθ1cosθ

We know that sin^2theta + cos^2theta = 1sin2θ+cos2θ=1 so

cos^2theta = 1 - sin^2thetacos2θ=1sin2θ and

costheta = sqrt(1-sin^2theta)cosθ=1sin2θ

Substituting these into the expression gives

sqrt(1-sin^2theta)/sintheta +sintheta/(1-sin^2theta)1sin2θsinθ+sinθ1sin2θ

=((1-sin^2theta)^(3/2) +sin^2theta)/(sintheta(1-sin^2theta)=(1sin2θ)32+sin2θsinθ(1sin2θ)