Area of a Triangle
Calculate the area of a triangle using A = ½bh (half base times height).
Step-by-step examples for any triangle.
The Formula
A = ½ × b × h
This formula calculates the area of any triangle when you know the base and the perpendicular height.
The height must be measured at a right angle to the base.
Variables
| Symbol | Meaning |
|---|---|
| A | Area of the triangle |
| b | Length of the base |
| h | Perpendicular height (measured at 90° to the base) |
Example 1
Find the area of a triangle with base 10 cm and height 6 cm
A = ½ × b × h = ½ × 10 × 6
A = ½ × 60
A = 30 cm²
Example 2
A triangular sail has a base of 4.5 m and a height of 8 m. What is its area?
A = ½ × b × h = ½ × 4.5 × 8
A = ½ × 36
A = 18 m²
When to Use It
Use this formula when:
- You know (or can measure) the base and the perpendicular height
- Calculating the area of triangular land plots, roofs, or surfaces
- Breaking complex shapes into triangles to find their total area
- For triangles where you only know side lengths, use Heron's formula instead