1. Not finding help here? Sign up for a free 30min 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!

A problem in Trigonometry (Properties of Triangles) v2

  1. May 11, 2017 #1
    1. The problem statement, all variables and given/known data

    In any triangle ABC, prove that $$ a^2 + b^2 +c^2 =4 \Delta (\cot {A}+\cot {B}+\cot {C}) $$

    2. Relevant equations

    3. The attempt at a solution

    14945181329111154603192.jpg
     
  2. jcsd
  3. May 11, 2017 #2
    What is ##\Delta## ?
     
  4. May 11, 2017 #3
    The area of Triangle, the standard notation used in Trigonometry.
     
  5. May 11, 2017 #4
    ##\displaystyle {c \over \sin c} = 2R##

    Check your work again, you replace ##\sin c## with ##a/(2R)##, you should do ##c/(2R)##
     
  6. May 11, 2017 #5
    You are wrong: $$\frac {c} {\sin (c)} = 2R$$ not $$\frac {c}{\sin ^2 (c)} = 2R$$
     
    Last edited by a moderator: May 11, 2017
  7. May 11, 2017 #6
    Yes, that was a typo. o0)o0):-p
     
    Last edited by a moderator: May 11, 2017
  8. May 11, 2017 #7

    Mark44

    Staff: Mentor

    No, this is not standard notation for the area of a triangle. Δ is sometimes used for the discriminant of a quadratic equation, but I have never seen it used for area of any kind.
     
  9. May 12, 2017 #8
    Although notations shouldn't very, h ere in India we use Delta to distinguish the area of the triangle only on Trigonometry.

    Discriminant is shown by D.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: A problem in Trigonometry (Properties of Triangles) v2
Loading...