Cos x+ 2cosx + Sinx=0 solve the equation for the interval [0,2pi]

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Reggaemahn · Answer 1 · 2019-02-07T13:41:55+0000

cos²(x) + 2cos(x) + sin²(x) = 0
Note: cos²(x) + sin²(x) = 1
2cos(x) + 1 = 0
2cos(x) = -1
cos(x) =
- (1)/(2)

120 degrees and 240 degrees →
$(2)/(3) \pi$ and
$(4)/(3) \pi$