Question

express sin 3theta in terms of sin theta

Answer 1

http://en.wikipedia.org/wiki/List_of_trigonometric_identities

Answer 2

It's located under Double-, triple-, and half-angle formulae

Answer 3

\[\sin(3 \phi)=\frac{e^{3i \phi}-e^{-3i \phi}}{2i}\]
Then use:
\[e^{3i \phi}=(e^{i \phi})^3; e^{i \phi}=\cos(\phi)+i \sin(\phi)\]
Then set the real part equal.

Answer 4

thanks but i do not really understand the working out

Answer 5

If you know the formula for \[\sin (A+B)\]
then you can derive the formula for
\[\sin 2A = \sin (A + A)\]
and
\[\sin 3A = \sin (A + 2A) \]