Answer
$$t=\frac{\pi }{3},\:t=\frac{5\pi }{3}$$
Work Step by Step
Using inverse trigonometric functions to solve the equation, we find:
$$\cos \left(t\right)=\frac{1}{2},\:0\le \:t\le \:2\pi \\ t=\frac{\pi }{3}+2\pi n,\:t=\frac{5\pi }{3}+2\pi n \\ t=\frac{\pi }{3},\:t=\frac{5\pi }{3}$$