How many lines of symmetry are in a triangle?

The number of lines of symmetry of a triangle depends upon the kind of triangle it is:

• A scalene triangle with no side lengths equal has no lines of symmetry;
• An isosceles triangle with two sides equal has 1 line of symmetry that bisects the angle between the two equal sides;
• An equilateral triangle with all three sides equal has three lines of symmetry - the three lines are the bisectors of the three angles.

A right triangle is a triangle where one angle is 90°. A right triangle is either a scalene triangle with no lines of symmetry or an isosceles triangle (where the legs are of equal length) with one line of symmetry which bisects the 90° angle.

No triangle can have exactly 2 lines of symmetry.