SOLUTION: Solve the following equation in the interval [0, 2pi]. Give the answer as a multiple of pi. Do not use decimal numbers. The answer should be a fraction or an integer. 2(cos(t))

Algebra ->  Trigonometry-basics -> SOLUTION: Solve the following equation in the interval [0, 2pi]. Give the answer as a multiple of pi. Do not use decimal numbers. The answer should be a fraction or an integer. 2(cos(t))      Log On


   

Question 928620: Solve the following equation in the interval [0, 2pi].
Give the answer as a multiple of pi. Do not use decimal numbers. The answer should be a fraction or an integer.
2(cos(t))^2-cos(t)-1=0.
I really need some help figuring this out, please.
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Solve the following equation in the interval [0, 2pi].
2(cos(t))^2-cos(t)-1=0.
(2cos(t)+1)(cos(t)-1)=0
..
2cos(t)+1=0
cos(t)=-1/2
t=2π/3, 4π/3
..
cos(t)-1=0
cos(t)=1
t=0, 2π