Area of a Triangle Lesson
A triangle is a three-sided polygon. Triangles are one of the most basic geometric shapes, and their properties can be used to determine the area of many other polygons. A right triangle is a triangle which has one 90 degree angle between sides. An equilateral triangle is a triangle which has three sides of equal length with equal angles between them. An Isosceles triangle is a triangle which has two equal sides and two equal angles.
The formula for the area of a triangle is:
where a is the length of the base, and h is the height. You can think of the area of a triangle as being half of the area of a rectangle with sides a and h.
If a rectangle has a base of length 3 and height of 4, for example, the area is