Posted by Bob on .
I need to find the solutions in the interval [0, 2pi for:
2sinx + cosx = 0
Im trying to get it where I can split two things up and set them equal to zero but that can only be done when they are being multiplied to each other, but as you can see they are being added, so they cannot be separated.

Math  Trig 
Reiny,
how about,
2sinx = cosx, now divide by cosx
2sinx/cosx = 1
sinx/cosx 1/2
tanx = 1/2
take inverse tan (+.5) to get 26.57ยบ
the tangent is negative in quadrant II and IV
the angle is 18026.57 and
36026.57
Just noticed that you need radians, set your calculators on Radians, find the angle in standard position, then do
pi  angle and 2pi  angle.