1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Trig Equations

  1. Apr 19, 2004 #1
    Solve 2cos^2(x)+cos(x)-1=0 In the interval where x is greater or equal to 0 and less than or equal to 2pi

    Let cos(x)=y

    2y^2+y-1=0 Factors to
    so y=1/2 or y=-1
    cos(x)=-1 so x=pi
    cos(x)=1/2 Here is my question, I know it equals pi/3, but can it also equal 5pi/3 ?
    If someone would let me know I would greatly appreciate it
  2. jcsd
  3. Apr 19, 2004 #2
    Plug it into the equation. What do you get?

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook