# CBSE Class 10-Mathematics: Chapter – 13 Surface Areas and Volumes Part 25 (For CBSE, ICSE, IAS, NET, NRA 2022)

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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.

**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