Question

Use De Moire's Thrm to compute: 3√(8cos(4pi/5)+8isin(4pi/5))
Im really confused on this one

Answer 1

Hi

Answer 2

You're dealing with 3 sqrt 8 * sqrt(of your trig) yes? Because sqrt(ab) = sqrt(a)*sqrt(b)

Answer 3

Looks it's a cube root

Answer 4

Hi guys! Yes, I believe so. I haven't done this sort of problem. I have only solved for the roots before.

Answer 5

Is 3 times all that jelly under the root?

Answer 6

Or the 3rd root of all that?

Answer 7

So we're all on the same page

Answer 8

It is all under the root I think, how i typed it out is how it is set up.

Answer 9

a square root then?

Answer 10

Yes

Answer 11

Okay, so De Moivre's Theorem says that if you have (cos(x)+isin(x)) to some power let's say n, that's equal to cos(nx)+isin(nx). And a square root of function happens to be equivalent to taking that function to the one half power.

Answer 12

Now does that clear things up?

Answer 13

Yes! Thank you :)