- #1

kathrynag

- 598

- 0

## Homework Statement

Derive from Demoivre's theorem that

cos2theta=(costheta)^2-(sintheta)^2

sin2theta=2sin theta costheta

## Homework Equations

## The Attempt at a Solution

I really am clueless on this.

I considered using (costheta +isintheta)^n, but don't know where to go with this idea.

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