Here's the problem ... I am not getting the right concept to apply here. I have tried to replace 5cos^2 theta with (1 - sin^2 theta) but I cannot reach a conclusion at all.

I have to find the roots in the interval 0 <= theta <= 360 correct to 1 decimal place.

$\displaystyle 10sin^2 \theta - 5cos^2 \theta + 2 = 4sin \theta$

P.S. I am not sure how to add degree subscript character in latex on this forum.