SOLUTION: solve equation for solution (0 deg, 360 deg) 4 cos ^2 theta +4 cos theta = 1. I used the quadratic formula, but get stuck.

Question 955450: solve equation for solution (0 deg, 360 deg) 4 cos ^2 theta +4 cos theta = 1.
I used the quadratic formula, but get stuck.
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
solve equation for solution (0 deg, 360 deg) 4 cos ^2 theta +4 cos theta = 1
4cos^2(x)+4cosx=1
4cos^2(x)+4cosx-1=0
solve for cosx by quadratic formula:

a=4, b=4, c=-1
ans:
cosx=-1.207 (reject)(-1 ≤ cosx ≤1)
or
cosx=0.207
x≈78.05˚, 281.95˚
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