Question

prove that cos(90-theta)= sin theta​

Answer 1

Answer:

The case in which P is on a coordinate axis is easily handled separately. Now, sine is an odd function, which means that sin(−θ)=−sinθfor all θ. Putting these together: cos(θ+90∘)=cos(90∘−(−θ))=sin(−θ)=−sinθ.