How do you verify the identity tan(θ+π2)=−cotθ?
1 Answer
Jun 16, 2018
Explanation:
using the addition formulae for sin/cos
∙xsin(x+y)=sinxcosy+cosxsiny
∙xcos(x+y)=cosxcosy−sinxsiny
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)=cosθ−sinθ=−cotθ as required