How to Calculate the Area of an Isosceles Triangle

Geometry is a required course for all high school students. The study of triangles is one of the main topics in geometry, and finding the area is one of the main topics in studying triangles. One specific kind of triangle is the isosceles triangle. It is a fairly simple process to find the area of an isosceles triangle.

Things You'll Need

• Calculator

Instructions

The Area of an Isosceles Triangle

1. 

   Identify the parts of the triangle. The two sides that have the same length are called the "legs" of the triangle. The base is the side that has a different length. The height is the length from the point where the two legs meet to the middle of the base.

2. Multiply the length of the height by the length of the base.

3. Divide the product of the height and the base by 2. This number is the area of the triangle. The units of the area should be expressed as the square of the units. For example, if the height is 4 inches and the base is 6 inches, then the area will be 12 square inches, or 12 in^2.

Special Isosceles Triangle: Equilateral Triangle

1. 

   Identify the parts of an equilateral triangle. Because all the sides are the same length, it does not matter which side is the base or which sides are the legs. The height of the triangle is still the length from the point where the two legs meet and the middle of the base.

2. Multiply the length of the base by the length of the height.

3. Divide the product of the height and the base by 2. This number is the area of the triangle. The units of the area should be expressed as the square of the units. For example, if the height is 5.19 inches and the base is 6 inches, then the area will be 15.6 square inches, or 15.6 in^2.

Tips & Warnings

• Draw your own picture of the triangle and label all the sides. Drawing your own triangle will force you to notice everything about the picture.