measurement · Year 6 · Suggested learning sequence
Area of a parallelogram
Cut the triangle off one end of a parallelogram and slide it to the other end: you get a rectangle with the same base and height. So the area of a parallelogram is base × height. The height is the perpendicular height, at right angles to the base, not the slanted side. There is no ½, because a parallelogram is two whole triangles. If you know the area and one length, divide to find the other: height = area ÷ base.
Sample questions
This parallelogram has a base of 11 cm and a perpendicular height of 3 cm. What is its area in square centimetres?
- Cut the triangle off one end and move it to the other: the parallelogram becomes a rectangle. Area = base × height.
- The base is 11 cm and the height is 3 cm.
- 11 × 3 = 33 cm².
Answer: 33
This parallelogram has a base of 8 cm and a perpendicular height of 3 cm. What is its area in square centimetres?
- Cut the triangle off one end and move it to the other: the parallelogram becomes a rectangle. Area = base × height.
- The base is 8 cm and the height is 3 cm.
- 8 × 3 = 24 cm².
Answer: 24
This parallelogram has a base of 9 cm and a perpendicular height of 3 cm. What is its area in square centimetres?
- Cut the triangle off one end and move it to the other: the parallelogram becomes a rectangle. Area = base × height.
- The base is 9 cm and the height is 3 cm.
- 9 × 3 = 27 cm².
Answer: 27