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 moment I read the reply you got, I've been waiting to see if you asked that. You are probably not expected to know those exact values. Have you asked your instructor if you do?
The derivation of them is not straightforward (but someone will do it if you really really want to know).