# Equivalent expression for sinx^3

## Homework Statement

Find an equivalent expression for sin3x in terms of function values of x, 2x, 3x, raised only to the first power.

## The Attempt at a Solution

stuck! dont know where to begin I am reviewing for my exam right now I remember doing one of these problems before but I cant remember how.

sinx(sinx2)

sinx[(1-cos2x)/2]

am i on the right track?

## Answers and Replies

tiny-tim
Science Advisor
Homework Helper
Find an equivalent expression for sin3x in terms of function values of x, 2x, 3x, raised only to the first power.

stuck! dont know where to begin I am reviewing for my exam right now I remember doing one of these problems before but I cant remember how.

sinx(sinx2)

sinx[(1-cos2x)/2]

am i on the right track?

Hi synergix! (btw, don't write (sinx2), write either (sinx)2 or sin2x)

Your equation is correct, but I don't think it's what they're asking for …

it has a (sinx)(cos2x) … if you're allowed that, you might as well have (sinx)(sinx)(sinx).

I think they want a sum of first powers, each on its own.

Hint: start at the end …

what is sin(3x) in terms of powers of sinx? 