Hi, The question asks Solve for 'theta' cos2theta=sintheta x costheta.
Substituting for cos2th either 1-2sin^2th or 2cos^2th does not give an equation in either sine or cosine alone how do I solve this please?

Hi Alastair,

Try using the fact that $\sin(2 \theta) = 2 \sin(\theta) \cos(\theta).$

Penny

Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.