Class 9 | Chapter 13 | Surface areas and Volumes | Exercise 13.3 | Question 2

Question 2: Find the total surface area of a cone, if its slant height is 21 m and diameter of its base is 24m.

Cone

Cone is an interesting geometric figure to understand and work upon. You come across so many items in daily life that are conical in shape – like a picnic tent, an ice cream cone, a birthday cap and there are many more that you can think about.

In this chapter we will work on only right circular cones. To understand what a right circular cone is, watch the following video.

 

Lateral or curved surface area of cone = πrl

r = base radius, l = slant height

Total surface area of cylinder = πrl + πr² = πr (l + r)

r = base radius, l = slant height

To understand the above mentioned formulas, watch the following video. It is highly recommended to watch it before you attempt any cone related questions.

What is Area / Surface area / Volume

It is recommended to understand the core concept of area, surface area and volume before we attempt any question based on these concepts.

 

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