# The slant height of a frustum of a cone is 4 cm and the perimeters (circumferences) of its circular ends are18 cm and 6 cmthen the curved surface area of

the frustum is _______. 1

1
by starwin

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the frustum is _______. 1

1
by starwin

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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.