How do you verify the identity tan(θ+π2)=cotθ?

1 Answer
Jun 16, 2018

see explanation

Explanation:

using the addition formulae for sin/cos

xsin(x+y)=sinxcosy+cosxsiny

xcos(x+y)=cosxcosysinxsiny

tan(θ+π2)=sin(θ+π2)cos(θ+π2)

sin(θ+π2)=sinθcos(π2)+cosθsin(π2)

××××=sinθ(0)+cosθ(1)=cosθ

cos(θ+π2)=cosθcos(π2)sinθsin(π2)

××××=cosθ(0)sinθ(1)=sinθ

tan(θ+π2)=cosθsinθ=cotθ as required