1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    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 help ! !

  1. Jul 12, 2011 #1
    1. The problem statement, all variables and given/known data
    will sum1 prove this ........@=theta
    1-cos@ / sin@ = tan(@/2)

    2. Relevant equations

    3. The attempt at a solution
    i tried to do this
    cos@ = cos^2(@/2) - sin^2 (@/2)
    wat now?
    thats doesnt get me anywhere
    Last edited: Jul 12, 2011
  2. jcsd
  3. Jul 12, 2011 #2


    User Avatar
    Homework Helper

    Since you have a half angle on the right side, you'll want to convert all angles into their half angle equivalents. For example, [tex]\sin(2x)=2\sin(x)\cos(x)[/tex] therefore [tex]\sin(\theta)=2\sin\left(\frac{\theta}{2}\right) \cos \left(\frac{\theta}{2}\right)[/tex]
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Threads - Trigonometry help Date
Help describing a region in polar coordinates Apr 21, 2017
Trigonometry Question Help Mar 5, 2017
What is 2nd sine? Jun 14, 2016
Help with law of sines/solving triangles Dec 10, 2014
Need help with trigonometry May 27, 2013