View Full Version : Length of a triangle
ray13971
Nov 28, 2010, 12:10 PM
The lengths of the sides of a triangle are consecutive even integers.Find the length of the longest side if it is 14 units shorter than the perimeter
galactus
Nov 28, 2010, 01:58 PM
Since the sides are consecutive even integers, it has perimeter
P=x+(x+2)+(x+4)
If you are familiar with Pythagorean triangles, this alone gives away the solution.
By Pythagoras:
x^{2}+(x+2)^{2}=(x+4)^{2}
Solve for x. You will notice the length of the hypoteneuse is 14 shorter than the perimeter.
It works out that way.
harum
Nov 28, 2010, 09:53 PM
If you are familiar with Pythagorean triangles, this alone gives away the solution.
Looks like we have no reason to assume that the solution is a right angle triangle and ignore that the perimeter is longer than the longest side by a certain number.
Wouldn't it be just this (here a is the shortest side)?
a + (a+2) + (a+4) = (a+4) + 14 => a = 6 and so on.
Unknown008
Nov 29, 2010, 02:12 AM
I was thinking this as well... the triangle is not necessarily a right angled triangle.
Or, if we want to go faster, we do:
Let the longest side be x.
P - 14 = x
P = (x-4) + (x-2) + x
[(x-4) + (x-2) + x] - 14 = x
galactus
Nov 29, 2010, 02:24 PM
Yes, my bad. False assumption.
Force of habit. I am so used to these problems involving right triangles.
Coincidentally, I had just gone over a problem that stated "one side of a right triangle is 7 units more than the short side, and the hypoteneuse is 8 more than the short side. What are the side lengths?".