WAEC - Mathematics (1988 - No. 32)
A cone is made from a sector of circle of radius 14cm and angle of 90o. What is the area of the curved surface of the cone? (Take x = 22/7)
22cm2
38.5cm2
77cm2
154cm2
308cm2
Giải thích
Length of arc =
θ360
* 2πr=> r =
90360
* 144
= 3.5 slant height t = 14cm
curved surface area of cone = πrl
=> 3.142 x 3.5 x 14 = 153.95