Question

2 cos(θ) + 9 = 8

equation on the interval 0< θ < 2π

solving for θ

Answer 1

\[2\cos(\theta)+9=8\\
2\cos(\theta)=-1\\
\cos(\theta)=-\frac{1}{2}\] is a start
then find the two values of \(\theta\) in \(0\leq \theta<2\pi\) where \(\cos(\theta)=-\frac{1}{2}\)

Answer 2

so would it be 2π/3 and 4π/3