In this section we calculate the area of various shapes.
Area of a circle | = | π r² | |
Area of a triangle | = | b h | |
Area of a parallelogram | = | b h |
Calculate the area of the triangle shown.
Area = × 4 × 6 = 12 cm²
Calculate the area of a circle with diameter 10 m.
Radius = 10 ÷ 2 = 5 m
Area = π × 5² = 78.53981634 m² = 78.5 m² (to 3 significant figures)
Calculate the area of the shape shown:
Area of rectangle = 4 × 8 = 32 m²
Radius of semicircle = 4 ÷ 2 = 2 m
Area of semicircle = × π × 2² = 6.283185307 m²
Total area = 32 + 6.283185307 = 38.283185307 m² ≈ 38.3 m²
The diagram shows a piece of card in the shape of a parallelogram, that has had a circular hole cut in it.
Calculate the area of the shaded part.
Area of parallelogram = 11 × 6 = 66 cm²
Radius of circle = 4 ÷ 2 = 2 cm
Area of circle = π × 2² = 12.56637061 cm²
Area of shape = 66 – 12.56637061 = 53.43362939 cm² ≈ 53.4 cm²