Question 976405
25cosa^2 + 5cosa - 12 = 0
(5cosa - 3)(5cosa + 4) = 0
cos a = 3/5 = 0.6
53.1 degs, 306.9 degs
or
cos a = -4/5 = -0.8
143.1 degs , 216.9 degs
Hope this helps:-)