I'm doing question #21c on page 56 of the manual.
Apart from moving the 2 over and finding a common factor, I'm not sure what to do.

post the question and i would be able to help most probably

Solve the equation:
cos^2x - cosx - 2 = 0

Don't you just isolate cos after that?

*hasn't used any of that trigonometry stuff since gr 12*
(is the answer 2? please tell me it's 2 >_>)
(or is it 1 and -2...) @[email protected]

thats a quadratic equation

cos^2 x - 2cos x + cos x - 2 =0

cosx (cosx - 2) +1 (cosx - 2) =0

(cosx +1) (cosx-2)

cosx != 2 so this solution is useless
cosx=-1

x= 180 degrees

I'm not sure if there is another solution aside from 180 degrees

what math course is this, looks like baby stuff lol (no offense)

Originally Posted by Afzal

what math course is this, looks like baby stuff lol (no offense)

Business student and I don't remember having to do sin/cos/tan stuff in 1M03 so I'm guessing one of those "if you didn't take it in gr 12" courses...

Just putting this out there but a site I found useful if you are struggling with a math problem at like 2am when no TA's are around especially a complicated integral or something lol is http://www.wolframalpha.com/. I used this site last year when my textbook didn't provide a solution and I was stuck. Heres an example of your question with steps: http://www.wolframalpha.com/input/?i=solve+cos^2+x+-+cos+x+-+2+%3D+0. (click 'show steps' to see it worked out)

The answer is (2k + 1)pi

This isn't from a particular course, just the Math Review Manual posted by the math Department
Thanks Afzal, Jeff and Colin

I just didn't realise it was a quadratic equation at first.
I got the same answer as you when solving x = pi but don't understand the correlation between that and the answer listed above

The method wolfram alpha uses is completing the square: http://www.purplemath.com/modules/sqrquad.htm

I GET IT I GET IT.
I DON'T FEEL DUMB ANYMORE.
TAKE THAT, TEACHER WHO SAID I JUST MEMORIZE THROUGH MATH.
I have finally broken the barrier and now I understand.