My Math Forum Area of a quadrilateral

 New Users Post up here and introduce yourself!

 July 2nd, 2014, 06:49 AM #1 Newbie   Joined: Jul 2014 From: India Posts: 1 Thanks: 0 Area of a quadrilateral Hey friends! New to this forum!! Can I find the area of a quadrilateral if just the lengths of all sides are known? I don't know the internal angles. Please help Thanks in advance!
 July 2nd, 2014, 10:25 AM #2 Math Team   Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 13,791 Thanks: 970
July 2nd, 2014, 11:37 AM   #3
Global Moderator

Joined: Nov 2006
From: UTC -5

Posts: 16,046
Thanks: 938

Math Focus: Number theory, computational mathematics, combinatorics, FOM, symbolic logic, TCS, algorithms
Quote:
 Originally Posted by shankarathreya Hey friends!
Welcome!

Quote:
 Originally Posted by shankarathreya Can I find the area of a quadrilateral if just the lengths of all sides are known? I don't know the internal angles.
No. Consider a rhombus: you can squeeze the opposite sides together, reducing the area, without changing the length of the sides.

If you know the lengths of the diagonals in addition to the lengths of the sizes then you can find the area, though. Also (as mentioned above) you can do it if you know the quadrilateral can be inscribed in a circle using Brahmagupta's formula (the extension of Heron's formula to quadrilaterals).

July 2nd, 2014, 11:38 AM   #4
Math Team

Joined: Dec 2006
From: Lexington, MA

Posts: 3,267
Thanks: 407

Hello, shankarathreya

Quote:
 Can I find the area of a quadrilateral if just the lengths of all sides are known?

Think about it . . .

Suppose we have a quadrilateral with four equal sides.
What is its area?

Code:
                  *  *  *  *  *
*             *
*             *
*             *
*  *  *  *  *

*  *  *  *  *
*             *
*             *
*             *
*             *
*  *  *  *  *
How can we find its area when we don't know its shape?

 Thread Tools Display Modes Linear Mode

 Similar Threads Thread Thread Starter Forum Replies Last Post Albert.Teng Algebra 6 July 5th, 2012 04:56 AM panky Algebra 2 December 18th, 2011 09:39 PM mateus1165 Algebra 3 November 23rd, 2011 10:32 AM michary91 Algebra 2 September 29th, 2010 05:34 AM meph1st0pheles Algebra 4 February 25th, 2010 11:40 AM

 Contact - Home - Forums - Cryptocurrency Forum - Top