Mathematics for IGCSE & O level - Mensuration (Section 8 - No. 13)
If the circumference of a circle is 31.4 cm, what is its approximate radius?
2.5 cm
5 cm
10 cm
15 cm
คำอธิบาย
Circumference = 2 * pi * radius. radius = circumference / (2 * pi). radius = 31.4 / (2 * 3.14) = 5cm