How it works
A triangle is half of the rectangle round it. Base times height, then half.
A = 1/2 × base × height.
The height is measured straight up from the base, at a right angle.
Worked examples
A whole-number triangle
- A triangle has base 9 ft and height 8 ft. What is its area?
- Base 9, height 8.
- 9 × 8 = 72, and half is 36.
- So the answer is 36.
A fraction height
- A triangle has base 1 units and height 7/2 units. What is its area?
- Base 1, height 7/2.
- 1 × 7/2 = 7/2, and half is 7/4.
- So the answer is 7/4.
A sail
- Mia sews a triangle sail. The base is 4 meters. The height is 3 meters. What is the area?
- Base 4 meters, height 3 meters.
- 4 × 3 = 12, and half is 6.
- So the answer is 6.
A taste of the worksheet
These are the first problems of set A. The printable sheet has many more, with an answer key.
- A triangle has base 6 cm and height 6 cm. What is its area__
- A triangle has base 3 ft and height 6 ft. What is its area__
- A triangle has base 9 m and height 6 m. What is its area__