The Wonderful World of the Triangle Inequality Theorem

The triangle inequality theorem says any two sides of a triangle must add to more than the third. It is the test for whether three given lengths can form a triangle at all, and it also bounds the range of a missing side.

Practice questions on the triangle inequality theorem

1. Can sides of lengths (4 text{ cm}), (7 text{ cm}), and (13 text{ cm}) form a triangle?
2. Can sides of lengths (9 text{ cm}), (11 text{ cm}), and (20 text{ cm}) form a triangle?
3. Can sides of lengths (15 text{ cm}), (17 text{ cm}), and (31 text{ cm}) form a triangle?

1. No
2. No
3. Yes

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