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How to Determine if Three Side Lengths Are a Triangle

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Determine if Three Side Lengths Are a Triangle

If you have been given three side lengths, and are asked to find out if they are a triangle, don't freak out! Just use this simple formula to figure it out.

Edit Steps

  1. 1
    Learn the formula. It is a series of three inequalities: a+b>c, a+c>b, and b+c>a. For this example, a=7, b=10, and c=5.
  2. 2
    Plug in the three numbers where they belong
    • 7+10>5
    • 7+5>10
    • 10+5>7
  3. 3
    Solve inequalities.
    • 17>5
    • 12>10
    • 15>7
  4. 4
    Interpret the inequalities.
    • If all the inequalities are true, then the three sides make a triangle.
    • If at least one inequality is false, then the three sides will not form a triangle.

Edit Tips

  • This is foolproof as long as you do the math right, and it is basic addition, so it is very simple.

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Article Info

Last edited:
July 9, 2012 by The Guitarist

Categories:
Geometry

Recent edits by: Oliver, Andrew, BR (see all)

In other languages
Español: Como saber si hay un triángulo teniendo las medidas de tres lados

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