Solve the equation on the interval $$0 \leq \theta

Question

Solve the equation on the interval $$0 \leq \theta < 2 \pi$$
-$2 \cos \theta + 1 = 0$
A) $\frac { 2 \pi } { 3 } , \frac { 4 \pi } { 3 }$
B) $\frac { \pi } { 3 } , \frac { 5 \pi } { 3 }$
C) $\frac { 3 \pi } { 2 }$
D) $\frac { \pi } { 2 } , \frac { 3 \pi } { 2 }$

Quizplus · Accepted Answer

First, solve for $\cos \theta$ by subtracting 1 from both sides and then dividing by 2, giving $\cos \theta = -\frac{1}{2}$. The angles in the interval $[0, 2\pi)$ where the cosine value is $-\frac{1}{2}$ are $\frac{2\pi}{3}$ and $\frac{4\pi}{3}$.

Solve the Equation on the Interval 0≤θ<2π0 \leq \theta < 2 \pi0≤θ<2π

Solve the Equation on the Interval $0 \leq \theta < 2 \pi$