Acute, Right, Obtuse Triangle Tester
Input Triangle Sides       A= B= C=

                   

Sum of the squares of 2 smallest sides  Longest Side Squared

             



CALCULATOR   INSTRUCTIONS

Input 3 triangle side lengths (A, B and C), then click "ENTER". This calculator will determine whether those 3 sides will form an equilateral, isoceles, acute, right or obtuse triangle or no triangle at all.

Without Using The Calculator
When given 3 triangle sides, to determine if the triangle is acute, right or obtuse:

1) Square all 3 sides.

2) Sum the squares of the 2 shortest sides.

3) Compare this sum to the square of the 3rd side.

if sum > 3rd side²   Acute Triangle

if sum = 3rd side²   Right Triangle

if sum < 3rd side²   Obtuse Triangle




Here are three examples:
5, 6 and 7 Each side squared = 25, 36 and 49

sum of the squares of the short sides = 25 + 36 = 61

61 > 49 Acute Triangle


3, 4 and 5 Squaring each side = 9, 16 and 25

sum of the squares of the short sides = 9 + 16 = 25

25 = 25 Right Triangle


3, 7 and 9 Squaring each side = 9, 49 and 81

sum of the squares of the short sides = 9 + 49 = 58

58 < 81 Obtuse Triangle


For determining if the 3 sides can even form a triangle, the triangle inequality theorem states that the longest side must be shorter than the sum of the other 2 sides.



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