Area of Triangles
Calculate the area of triangles
Area of Triangles
The area of a triangle = ½ × base × height. The height must be perpendicular (at right angles) to the base. A triangle is half of a rectangle with the same base and height.
Example
Calculating Triangle Area
A triangle with base = 10 cm and height = 6 cm:
Area = ½ × 10 × 6 = 30 cm²
A triangle with base = 8 m and height = 5 m:
Area = ½ × 8 × 5 = 20 m²
Finding the Height
The height is the perpendicular distance from the base to the top vertex. It is NOT always a side of the triangle. Draw a line from the top corner straight down to the base at 90°.
Note
Remember
Area of triangle = ½ × base × height. The height must meet the base at a right angle (90°). Units are always squared (cm², m²).
Key Vocabulary
BaseThe bottom side of a triangle
HeightThe perpendicular distance from base to opposite vertex
PerpendicularAt right angles (90°)
VertexA corner point of a shape
AreaThe space inside a shape measured in square units
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