Elementary equation in cosine

Statement

Solve the trigonometric equation: $2\cos x - 1 = 0$

Solution

Isolating the cosine yields an elementary equation: $\cos x = \frac{1}{2}.$ Since $\arccos(1/2) = \pi/3$, the solutions are $\boxed{\,x = \pm\frac{\pi}{3} + 2k\pi,\quad k\in\mathbb{Z}.}$

Links

Topics: Trigonometric equations
Concepts: Elementary equation
Functions: Cosine
Skills: Solving equations · Using formulae
Exercise type: Solving an equation