Triangle Inequality Theorem
Video Tutorial on the Triangle Inequality Theorem
Demonstrations illustrating the Triangle Inequality Theorem
The interactive demonstration below shows that the sum of the lengths of any 2 sides of a triangle must exceed the length of the third side. The demonstration also illustrates what happens when the sum of 1 pair of sides equals the length of the third side--you end up with a straight line! You can't make a triangle!
Otherwise, you cannot create a triangle from the 3 sides.
Demonstration 1: When the sum of 1 pair of sides exactly equals the measure of a 3rd side.
Demonstration 2 When the sum of 1 pair of sides is less than the measure of a 3rd side.
Problem 1) Could a triangle have side lengths ofPractice Problems II
Side 1: 4
Side 2: 8
Side 3: 2
Use the triangle inequality theorem and examine all 3 combinations of the sides. As soon as the sum of any 2 sides is less than the third side then the triangle's sides do not satisfy the theorem.
problem 2) Could a triangle have side lengths of
Side 1: 5
Side 2: 6
Side 3: 7
Use the shortcut and check if the sum of the 2 smaller sides is greater than the largest side .
problem 3) Could a triangle have side lengths of
Side 1: 6
Side 2: 8
Side 3: 15
problem 6) Two sides of a riangle have lengths 2 and 7. Find all possible lengths of the third side.
problem 7) Two sides of a riangle have lengths 12 and 5. Find all possible lengths of the third side.