Definition
Equilateral triangle
An equilateral triangle is a triangle whose three sides all have the same length.
Continue from this idea into connected AXIO math.
What it means
Check all three sides, not the way the triangle is turned. If every side has the same length, the triangle is equilateral. That equal-sided shape also makes three equal 60° angles.
Remember it
Equilateral means equal sides: all three match.
Example
Draw a triangle with side lengths 5 cm, 5 cm, and 5 cm. Because all three sides are equal, it is equilateral; each interior angle is 60°.
Watch for
A triangle with side lengths 5 cm, 5 cm, and 4 cm is isosceles but not equilateral.
Common mix-up
Using the inclusive definition of isosceles—at least two equal sides—every equilateral triangle is also isosceles.
Exact meaning
An equilateral triangle is a triangle whose three sides have equal length. In Euclidean geometry, its three interior angles are equal and each measures 60°.