Originally Posted by
bobak This problem can easily be solved my comparing coefficients.
First start by stating your identity.
$\displaystyle R \cos(x - \alpha) \equiv 3 \sin x + 4 \cos x $
It is important that you understand exactly what $\displaystyle \equiv$ means before you go ahead, if you don't just say.
Expand the left hand side using the compound angle formula.
$\displaystyle R \cos x \cos \alpha + R \sin x \sin \alpha \equiv 3 \sin x + 4 \cos x $
compare coefficients to get
$\displaystyle R \cos \alpha = 4 $
$\displaystyle R \sin \alpha = 3 $
do you want to try and finish off form here ?
let me know how it goes form here.
Bobak