Question

How do you verify Cos( 225 -θ) = -sinθ ?

The 225 is in degrees, but I don't know how to put in 3pi/2 or a degrees symbol.

Answer 1

This one isn't true, try `theta=0`. We get `-sin theta = 0` but `cos 225^circ = - cos(225^circ - 180^circ) = -cos(45^circ)=-1/sqrt{2}`. Sorry.