trigonometry

penguin007

1. The problem statement, all variables and given/known data
Hi all,

I'm trying to prove that (16+4cos(2x))/(17+8cos(2x))=Re(1/(1+exp(2ix)/4);


2. Relevant equations



3. The attempt at a solution

I tried to use cos(x)=(exp(ix)+exp(-ix))/2, but it doesn't bring me that much...

Any indication is welcome...

Dick

To get the real part of 1/(1+exp(2ix)/4) you'll want to write in the form a+bi. Multiply numerator and denominator by the complex conjugate of the denominator. That will give you a real number in the denominator.