
Algebra PreAlgebra and Basic Algebra Math Forum 
 LinkBack  Thread Tools  Display Modes 
March 4th, 2013, 12:34 PM  #11 
Newbie Joined: Mar 2013 Posts: 8 Thanks: 0  Re: Find all the sides of this triangle.
For me. First: QB = PB CQ = RC follows that beta = angleQBP = 2*arctg(r/QB) gamma = angleQCR = 2*arctg(r/CQ) AC = CB * sin (beta) / sin(180° beta  gamma) = 13 AB = CB * sin (gamma) / sin(180° beta  gamma) = 15 
March 4th, 2013, 01:24 PM  #12  
Senior Member Joined: Sep 2010 Posts: 221 Thanks: 20  Re: Quote:
Correct x=7; AC=13; AB=15  
March 4th, 2013, 04:03 PM  #13 
Senior Member Joined: Dec 2012 Posts: 450 Thanks: 0  Re: Find all the sides of this triangle.
Bad news for everyone. I forgot to include the rule:don't use trignometry. 
March 4th, 2013, 05:12 PM  #14 
Global Moderator Joined: Dec 2006 Posts: 20,833 Thanks: 2161 
Trigonometry isn't needed to prove Heron's formula, and hence the formula I linked to originally.

March 4th, 2013, 05:15 PM  #15 
Senior Member Joined: Dec 2012 Posts: 450 Thanks: 0  Re: Find all the sides of this triangle.
I was referring to Mcpogor.

March 4th, 2013, 05:28 PM  #16 
Math Team Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 14,597 Thanks: 1038  Re: Find all the sides of this triangle.
No trig: Let b = AC; then AB = b+2 Using Heron's formula: s=(14 + b + b+2)/2 = b+8 ; leads to AreaABC = SQRT[48(b^2 + 2b  4] Carry on this way: SQRT[48(b^2 + 2b  4] = Area(triangles AOC + BOC + AOB) 
March 4th, 2013, 05:30 PM  #17 
Senior Member Joined: Dec 2012 Posts: 450 Thanks: 0  Re: Find all the sides of this triangle.
You got it,Denis...

March 4th, 2013, 05:37 PM  #18  
Math Team Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 14,597 Thanks: 1038  Re: Find all the sides of this triangle. Quote:
 
March 4th, 2013, 05:40 PM  #19 
Senior Member Joined: Dec 2012 Posts: 450 Thanks: 0  Re: Find all the sides of this triangle.
I am an Albert fan. And more than that these are the only sort of problems I think I can do good..... More to come from the Albert fan.... 

Tags 
find, sides, triangle 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
find the sides and angles of triangle  adilgrt007  Algebra  9  August 22nd, 2013 10:25 AM 
Find Remaining Angles and Sides of triangle  Britwells  Algebra  3  March 27th, 2013 01:31 PM 
find the angles and sides of the triangle  mathmaniac  Algebra  16  February 14th, 2013 06:27 PM 
Triangle sides...HELP  MathMathHelloMath  Algebra  3  October 13th, 2010 03:42 PM 
Triangle sides...HELP  MathMathHelloMath  Calculus  1  October 13th, 2010 06:06 AM 