Solve for [0, 360)

Question

2sinxcosx + cosx =0
2sinxcosx = -cosx
2sinx = -cosx/cosx
sinx = -1/2

{210, 330)

Is this correct?

Answer 1

no , you only have half the answers

2sinxcosx + cosx =0
cosx(2sinx + 1) = 0
cosx = 0 or sinx = -1/2

if cosx = 0, x = 90° , 270°
if sinx = -1/2, x = 210°, 330°

(you only had the last case)