The slant height of a frustum of a cone is 4 cm and the perimeter (cir

1.	The slant height of a frustum of a cone is 4 cm and the perimeter (circumference) of its circular ends are 18cm and 6 cm. Find the curved surface area of the frustum.
Answer» Given slant height(l)=4cm Circumference1(C1)=18cm 2 pie r1 = 18cm 222/7r1 = 18cm therefore, r1 = 63/22cm similarily C2 = 6cm so, r2 = 21/22cm now CSA of frustum of cone = pie l (r1+r2) 22/74(63/22+21/22) 84/22 4 * 22/7 =48 sq. cm.------------Ans.

The slant height of a frustum of a cone is 4 cm and the perimeter (circumference) of its circular ends are 18cm and 6 cm. Find the curved surface area of the frustum.

Answer»

Given slant height(l)=4cm

Circumference1(C1)=18cm

2 pie r1 = 18cm

2*22/7*r1 = 18cm

therefore, r1 = 63/22cm

similarily C2 = 6cm

so, r2 = 21/22cm

now CSA of frustum of cone = pie l (r1+r2)

22/7*4(63/22+21/22)

84/22 * 4 * 22/7

=48 sq. cm.------------Ans.