Question

What is sin theta when cos theta is 0

Answer 1

Divide by costheta

You get Sin(theta)/Cos(theta) + Cos(theta)/cos(theta) =0

[Sinx/cosx = tanx (a law of trigs)]

so the same as tan(theta) + 1=0

So tan(theta)=-1

Inverse tan/arctan (-1) =3/4 pi and (2pi - 3/4pi) = 7/4pi

Explanation: