A triangle is a polygon with 3 sides.

The interior angles of any triangle will add up to 180°.

Area of a Triangle

To find the area of a triangle, use this formula:

$$A = \frac{b × h}{2}$$

Equilateral Triangle

  • All sides the same length.
  • All angles the same size. (Each one is 60°.)

Isosceles Triangle

  • One line of symmetry.
  • Two sides the same length.
  • Two angles the same size.

Scalene Triangle

  • All sides different.

Right-Angled Triangle

  • Contains a right angle.