Question 651417
Find all values of x in the interval [0, 2π] that satisfy the inequality. (Enter your answer using interval notation.) 
2 cos(x) + 1 > 0
2cos(x) > -1
cos(x) > -1/2
{{{4pi/3 < x < 2pi/3}}}
solution:
(0,2&#960;/3) U (4&#960;/3,2&#960;)