The addition formula for sin is
si(A + B) = sinAcosB + cosAsinB.
Now spit 3x int (x + 2x) and then find
sin(x + 2x) =........
During simplification, try to replace cos terms by sin terms using trigonometric relations.
Part of question (from assignment): Use double-angle and addition formulæ and other relations for trigonometrical functions to find an expression for sin(3x) in terms of sin x alone.
I don't know what is meant by "to find an expression for sin(3x) in terms of sin x alone". I've found a working through of a very similar question but still don't get what is meant by it. I know how to "Use double-angle and addition formulæ and other relations for trigonometrical functions" but I don't get what I'm supposed to be doing with them.
This may seem stupid but I couldn't find an answer on google :/
Would really appreciate some help with this!
PS. This is actually for a university calculus paper but this seems like it would fit better here (sorry if it doesn't!).