Symmetry in triangles
Equilateral triangle
An equilateral triangle has:
- three equal sides
- three angles are equal (60°)
- three lines of symmetry
The three lines of symmetry are shown in this slideshow.
Image caption, Lines of symmetry
Three lines of symmetry on an equilateral triangle.
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End of image gallery
Isosceles triangle
An isosceles triangle has:
- two equal sides
- two equal angles
- one line of symmetry
Scalene triangle
A scalene triangle has:
- no equal sides
- no equal angles
- no lines of symmetry
Right-angled triangle
Right-angled triangles follow the same rules as other triangles. It's not the right angle that matters but whether the triangle is scalene or isosceles.
A right-angled scalene triangle has:
- one angle of 90°
- no equal sides
- no equal angles
- no lines of symmetry
A right-angled isosceles triangle has:
- one angle of 90°
- two equal sides
- two equal angles of 45°
- one line of symmetry
