Show that cos (θ-40) = sin (θ+50). Hence, or otherwise, solve the equation cos(θ-40) = sin(θ+50), giving all solutions between 0° and 360°.

Answer 1

by definition, costheta=sin(90-theta)
let theta=θ-40
then cos(θ-40)=sin(90-θ+40)
but sin (90-x)=sin(90+x)
then cos(θ-40)=sin(90+θ-40)=sin(θ+50)

Answer 2

Answer