Two Trigonometry questions?

Question

QUESTIONS:

(1) What exactly is an angle of depression?

(2) I have a trig question to solve and it is:

Find all solutions of the trig equation below in the interval
[0, 2pi).

sqrt{3}cos3x - 1 = 0

Answer 1

(1) The angle formed with one ray horizontal, and the other ray "depressed" as specified by the content of the problem/s.
(2) sqrt{3}cos3x - 1 = 0
cos 3x = 1/ sqrt{3} = sqrt{3} /3
3x = 2k*pi +- arc cos(sqrt{3} /3)
x = 2k*pi/3 +- arc cos(sqrt{3} /3)/3