Question

15cosx+27 sin^2 x+27cos^2 x=26​

Answer 1

$15cosx+27(sin^2x+cos^2x)=26\15cosx+27*1=26\15cosx=26-27\15cosx=-1\cosx=-frac{1}{15} \x=pm(pi -arccos(frac{1}{15}))+2pi  k, k in Z$