Question

A right circular cone has radius 5 cm and height 8 cm.  What is the lateral surface area of the cone​

Answer 1

Step-by-step explanation:

Curved Surface area of a frustum of a cone  =πl(r1+r2) where l is the slant height =h2+(r1−r2)2 h is the height. 

r1 and r2 are the radii of the lower and upper ends of a frustum of a cone.

So, l=162+(20−8)2

∴l=20cm

Hence, Curved surface area of this frustum of a cone  =π×20×(20+8)=560πcm2