- #1

- 22

- 0

## Main Question or Discussion Point

**Help! Euler's Relationship!**

if e^(i*theta) = cos(theta) + i*sin(theta)

then what is e^(-2i*theta) = ????

I attempted to derive this and got the following for the +2i:

e^(+2*theta) = cos(2*theta) + 2i*cos(theta)sin(theta)

Not even sure if this may be correct, but I believe the answer to my question with negative 2 (-2i) must be simple... Help please, thanx.

Because I am attempting to derive 2sin^2(theta) = 1-cos(2theta) from euler's relationship: e^(i*theta) = cos(theta) + i*sin(theta)

Hannah

Last edited: