solve the equation for solutions over the interval [0, 360)
4cos(squared)x + 4cosx = 1
I'm completely lost on this one!
Hi !
For you to better understand, substitute $\displaystyle u=\cos(x)$
The equation is now $\displaystyle 4u^2+4u=1$, that is to say $\displaystyle 4u^2+4u-1=0$
Now, use the method of discriminant or complete the square to get the solution
A slightly different way to do it is to substitute $\displaystyle u=2 \cos(x)$ ^^
no. as Moo said, the equation you are using is $\displaystyle 4 \cos^2 x + 4 \cos x - 1 = 0$
that is what you should be solving. she replaced cos(x) with you to make things look easier. just work on solving the quadratic equation she gave you. you can use the quadratic formula