# Homework Help: Verifing trig identities

1. Apr 3, 2010

### silversorrow

cos(x-(pie/2))=cos(x)tan(x)

I have to verify this identity and cant seem to figure it out. cos (x-y)=cos x * cos y + sin x * sin y
well since cos y = 0, it kind of eliminates that side of the equation and I end up with sinx * sin1