SMO 2016 Senior Round 1 Question 8
SMO · SMO 2016 Senior Round 1
Suppose $0^\circ\le x\le 180^\circ$. Find all the possible values of x such that $$3\cos^2(2 x)+4\sin(2 x)-\sin^2(2 x)=0.$$
$x=55^\circ,135^\circ$
$x=75^\circ,125^\circ$
$x=105^\circ,165^\circ$
$x=95^\circ,145^\circ$
$x=115^\circ,175^\circ$