Mathematics for IGCSE & O level - Mensuration (Section 1 - No. 39)
A cone has slant height 8 cm and curved surface area 63 cm². Calculate the total surface area of the cone.
70.3 cm²
88.5 cm²
94.2 cm²
87.9 cm²
解释
πrl=63. πrl = 63 ; Total surface area is πr²+πrl. We know CSA; So, CSA=πrl= 63 cm². From the CSA calculate the radius, r=63/πl=2.5 and total SA is 63 +πr²= 82.5cm²