Mathematics for IGCSE & O level - Mensuration (Section 7 - No. 6)
Calculate the base area of a cone with slant height 8.3 cm and curved surface area 52 cm²
25 cm²
15.8 cm²
30.4 cm²
36 cm²
คำอธิบาย
CSA = πrl = 52cm². l = 8.3 cm. r = 52 / (π*8.3) = 1.99. Base area is πr²= 3.14*1.99² ≈ 12.4 cm²