## anonymous 5 years ago cos x/2 = cos x. find all solutions in the interval [0,2π)?

1. anonymous

The general solution for cos(x)=a, is $n \pi \pm a$ Therefore, $x/2 = n \pi \pm x$ $x = 2n \pi \pm 2x$ $3x = 2n \pi | -x = 2n\pi$ $x = 2/3 n \pi | x = -2n \pi$ $[0,2 \pi], x=0 , 2 \pi / 3 , 4 \pi/3$ This is the solution set!

2. anonymous

Thank you so much!