Using identities to find the value of sin(2θ)

Question

What are the steps for finding sin(2θ) when given only the value of tanθ and cosθ is less than 0?

Answer 1

If cosine and tangent are negative, then sine must be positive, since tan = sin/cos

This happens in quadrant 2, with sin = tan * cos

sin(2T) = 2 sin T cos T where T is the angle theta