Mathematics for IGCSE & O level - Mensuration (Section 13 - No. 43)
If a circle has a diameter of 10cm, what is its area? (Use pi = 3.14)
31.4 cm²
78.5 cm²
15.7 cm²
62.8 cm²
Giải thích
Area = π * r^2 where r= diameter/2, so Area = 3.14 * (10/2)^2 = 3.14 * 25 = 78.5cm²