# Find the total surface area of a cone, if its slant height is 21 m and diameter of its base is 24 m. - Mathematics

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

["Assume "pi=22/7]

#### Solution

Radius (r) of the base of cone = (24/2)m = 12 m

Slant height (l) of cone = 21 m

Total surface area of cone = πr(r + l)

=[22/7xx12xx(12+21)]m^2

=(22/7xx12xx33)m^2

= 1244.57 m2

Concept: Surface Area of a Right Circular Cone
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#### APPEARS IN

NCERT Class 9 Maths
Chapter 13 Surface Area and Volumes
Exercise 13.3 | Q 2 | Page 221