HOW TO SOLVE THE EQUATION 2θ COS θ + θ = 0

Solve for θ
2θ COS θ + θ = 0
2θ COS θ = - θ

Dividing both sides by 2θ

(2θ COS θ)/2θ = - θ/2θ
COS θ = –½

Taking cos to right side

θ = cos−1(–½)
θ = 120° or 2π/3

Hello maria, you have not noticed that one of your answers is θ = 0 !!!

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rearrange the equation

2theta cos theta = - theta

divide by 2 theta
costheta = -1/2

so theta = 120 degrees

θ(2 COS θ + 1) = 0

θ = 0 or 2 COS θ + 1 = 0

2 COS θ + 1 = 0 => COS θ = - 1/2 => θ = 2npi +/-2pi/3

so θ = 0 or 2npi +/-2pi/3

2θ COS θ + θ = 0

θ(2cosθ + 1) = 0

θ = 0

2cosθ + 1 = 0
cos θ = -1/2
θ = 2(pi)/3