My Math Forum  

Go Back   My Math Forum > High School Math Forum > Algebra

Algebra Pre-Algebra and Basic Algebra Math Forum


Reply
 
LinkBack Thread Tools Display Modes
December 1st, 2011, 04:32 AM   #1
Member
 
Joined: Dec 2011

Posts: 61
Thanks: 0

perimeter

The triangle ABC has sides of length a,b and c.Show that perimeter of triangle ABC satisfies
p^2 = 2bc(1 + cos A) + 2ac(1 + cos B) + 2ab(1 + cos C)
najaa is offline  
 
December 1st, 2011, 05:14 AM   #2
Senior Member
 
MarkFL's Avatar
 
Joined: Jul 2010
From: St. Augustine, FL., U.S.A.'s oldest city

Posts: 12,211
Thanks: 521

Math Focus: Calculus/ODEs
Re: perimeter

The perimeter p is p = a + b + c. By the law of cosines, we may state:







Adding, we get:



Add 2ab + 2ac + 2bc to both sides:





MarkFL is offline  
Reply

  My Math Forum > High School Math Forum > Algebra

Tags
perimeter



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Perimeter of the triangle mared Algebra 2 January 29th, 2014 12:00 PM
Perimeter of a Sector bilano99 Algebra 2 March 13th, 2013 10:30 AM
area and perimeter tsl182forever8 Algebra 1 February 28th, 2012 10:58 PM
Perimeter question tatertots49 Algebra 1 May 18th, 2011 04:29 PM
Perimeter ExIsTaNcE Algebra 9 January 24th, 2010 05:52 AM





Copyright © 2019 My Math Forum. All rights reserved.