cos^2(x) + cos(x) = 2cos^2(x) - 1
cos^2(x) - cos(x) - 1 = 0
This is just like
u^2 - u - 1 = 0
u = [1 +/- sqrt(5)]/2
since u = cos(x) and must be less than 1,
cos(x) = (1-sqrt(5))/2
will be in QII or QIII
Solve Cos^2(x)+cos(x)=cos(2x). Give exact answers within the interval [0,2π)
Ive got the equation down to -cos^2(x)+cos(x)+1=0 or and it can be simplified too sin^2(x)+cos(x)=0
If you could tell me where to go from either of these two, it would be great help.. Thankyou for any responses
1 answer
1 answer