i got 3 tough trigonometry questions for you all. Hope you help me solve them out. If necessary i can show you the steps i tried out myself but for
the present i am limiting myself to the questions itself. any help would be highly appreciated and thanks in advance. the questions are with the attachment:
2cos2x - 2cosx + 1 = 0
4(cosx)^2 - 2 - 2cosx + 1 = 0
4(cosx)^2 - 2cosx - 1 = 0
cosx = -b +/- ......... quadratic forumla
Solving it, we get
cosx = (1 + root5)/4 or cosx = (1 - root5)/4
Therefore, x=36 degrees or x=144 degrees
And I suppose in the last one a, b and c add up to 180?
The derivation of them is not straightforward (but someone will do it if you really really want to know).