this is the double angle formula for cos
Im a little stuck on one of my questions and was hoping for a little bit of help.. So first, the question
Convert from polar to cartesian form, using double angle formula:
Ok, so things that I know:
The double angle formula which is reffered to, i believe is
But i could be wrong
The furthest i have got to in the problem so far is
And now im greatful if anyone is able to help me out please?
Thanks in advance!