I'm confused at how to use identities to solve problems such as sin(2theta)sin theta = cosine theta? Another example of a problem would be sin(2 theta) = cosine theta
Can anyone help?
Maybe try
$\displaystyle \sin 2\theta \sin \theta = \cos\theta$
$\displaystyle 2\sin \theta \cos\theta \sin \theta = \cos\theta$
$\displaystyle 2\sin \theta \sin \theta = 1$
$\displaystyle 2\sin ^2\theta = 1$
$\displaystyle \sin ^2\theta = \frac{1}{2}$
$\displaystyle \sin \theta = \frac{1}{\sqrt{2}}$
Can you finish it from here?