# Math - Trig

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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 -

2sinx = -cosx, now divide by cosx
2sinx/cosx = -1
sinx/cosx -1/2
tanx = -1/2

take inverse tan (+.5) to get 26.57º

the tangent is negative in quadrant II and IV

the angle is 180-26.57 and
360-26.57

Just noticed that you need radians, set your calculators on Radians, find the angle in standard position, then do
pi - angle and 2pi - angle.

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