Question

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

Answer 1

Given height of a bucket (R) = 24cm  

Radius of circular ends of bucket 5cm and 15cm

r1 = 5cm; r2 = 15cm

Let ''l be slant height of bucket

l = √ ( ( r1 - r2 )² + h² )

→ l = √ ( ( 15 - 5 )² + 24² )

→ l = √ ( 10² + 24² )

→ l = √ ( 100 + 576 )

→ l = √ 676

→ l = √ 26²

→ l = 26

Now Curved surface area of bucket

→ π ( r1 + r2 ) l

→ π ( 5 + 15 ) 26

→ π ( 20 ) 26

→ 22/7 × 20 × 26

→ ( 440 × 26 ) / 7

→ 11440 / 7

→ 1634.28 ( Ans )

Answer 2

if we draw the diagram of the fig.

then surely it forms a frustum :)

now let r1 = 5  & r2 = 15

L =  sq root (h2 + (r2 - r1)2 = 26

CSA of a frustum is pie x l (r1 + r2)

3.14 x 26 (15 + 5)

solving this

ans will come

1632.8