Triangle Inequality

The sum of any two sides of a triangle is greater than the third side

Easy

Practice Overview

Description: Drag the sliders to change the three side lengths and watch live: when it closes, the two shorter sides meet; when it fails, they lie flat and cannot reach the longest side. Three check chips compare every pair-sum with the third side.
Estimated Time: 10min
Tags: triangletriangle inequalityside lengthstwo sides sum
Access Level: Free

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About This Practice

Three sticks do not always make a triangle: the sum of any two sides must be greater than the third. With sides 3, 4, 8 we get 3+4<8 — the two short sticks lie flat and never touch, so no triangle can close.

Drag the sliders to change the three side lengths and watch live: when it closes, the two shorter sides meet; when it fails, they lie flat and cannot reach the longest side. Three check chips compare every pair-sum with the third side.

EasyEstimated Time: 10mintriangletriangle inequalityside lengthstwo sides sum

How to Play

Look at the three lengths and guess: will they close?

Watch the picture: do the short sides meet, or is there a gap?

Check the three chips: is every pair-sum greater than the third side?

Make one side longer or shorter to find the borderline case.

Tap “New Set” a few times and state the rule yourself.

Triangle Inequality

About This Practice

How to Play

Learning Objectives

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