# CBSE 10th Math Sample Paper 2019 | Q29

#### Surface Area of Frustum of Cone

This 2019 CBSE class 10 Maths 4 mark question is from Surface Areas. Concept covered in this 4-mark question that appeared in the 2019 sample question paper: Computing surface area of frustum of cone.

Question 29: The radii of the circular ends of a bucket of height 24 cm are 15 cm and 5 cm. Find the area of its curved surface.

## NCERT Solution to Class 10 Maths

#### With Videos

Height = BC = 24 cm
R = CE = 15 cm
r = AB = 5 cm
Curved Surface area of bucket (frustum of cone) = π × (R + r) × l

Step 1: Find slant height 'l' – AE is the slant height
Draw AD perpendicular to CE. ΔADE is a right triangle.
AD = BC = 24 cm
CD = AB = 5 cm
Therefore, DE = 15 – 5 = 10 cm
AE2 = AD2 + DE2
AE2 = 242 + 102 = AE2 = 576 + 100
AE =$$sqrt{676}$ = 26 Curved Surface area of bucket$frustum of cone) = π × (R + r) × l
= $$frac{22}{7}$ ×$15 + 5) × 26 = 1634.3 cm2

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