CBSE Class 10-Mathematics: Chapter –13 Surface Areas and Volumes Part 25
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Question 5:
Derive the formula for the curved surface area and total surface area of the frustum of a cone, given to you in Section , using the symbols as explained.

Derive the Formula for the Curved Surface Area
Answer:
According to the question, the frustum if difference of the two cones OAB and OCD (in figure)
For frustum, height , slant height and radii of the bases
Height of the cone
Height of the cone
V of the frustum V of cone of cone OCD
If and are the surface areas of two circular bases, then
of the frustum
Again, from
Hence, CSA of the frustum of the
TSA of the frustum of the cone