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!

Trigonometry question. Find the value of sinθ if cosθ=−1/4 and θ is in Quadrant II

  1. Sep 20, 2012 #1
    1. The problem statement, all variables and given/known data

    Question: Find the value of sinθ if cosθ=−1/4 and θ is in Quadrant II

    I have not done TRIG in a long time. Given this question, what should I read over/review ? I don't remember how to solve these types of questions?

    2. Relevant equations



    3. The attempt at a solution

    Not sure what kind of attempt I can do... I have to memorize the unit circle correct?

    P.S. - Thanks to Mark an Sammy for recent help - Got 93% on my first of 3 midterms :)
     
  2. jcsd
  3. Sep 20, 2012 #2

    hotvette

    User Avatar
    Homework Helper

    Re: Trigonometry question. Find the value of sinθ if cosθ=−1/4 and θ is in Quadrant I

    Might be good to draw a picture and remember the definition of cos in terms of lengths of sides of a right triangle. That should get you going in the right direction.
     
  4. Sep 20, 2012 #3

    LCKurtz

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Re: Trigonometry question. Find the value of sinθ if cosθ=−1/4 and θ is in Quadrant I

    Drawing a picture as hotvette suggests is an excellent idea. Another way is to use the fundamental identity ##\sin^2\theta + \cos^2\theta = 1## to solve for the cosine. The quadrant will help you choose the sign.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Trigonometry question. Find the value of sinθ if cosθ=−1/4 and θ is in Quadrant II
Loading...