SOLUTION: So I am in AP calc this year, and I have to do a review test, and can't find any of my old trig stuff.. So I was wondering if I could get a refresher on how to: Find all solutions

Algebra ->  Trigonometry-basics -> SOLUTION: So I am in AP calc this year, and I have to do a review test, and can't find any of my old trig stuff.. So I was wondering if I could get a refresher on how to: Find all solutions       Log On


   

Question 640630: So I am in AP calc this year, and I have to do a review test, and can't find any of my old trig stuff.. So I was wondering if I could get a refresher on how to: Find all solutions of the equation in the interval [0,2pi] A) 4cos(theta)=1+2cos(theta)
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
I'm going to use x in place of theta (it's easier to type)

4cos(x)=1+2cos(x)

4cos(x)-2cos(x) = 1

2cos(x) = 1

cos(x) = 1/2

x = arccos(1/2)

x = pi/3 or x = -pi/3

x = pi/3 or x = -pi/3+2pi

x = pi/3 or x = -pi/3+6pi/3

x = pi/3 or x = 5pi/3