Question

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

Answer 1

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

Answer 2

Given:

Height = 24 cm

Radius 1 = 5 cm

Radius 2 = 15 cm

To find:

Curved surface area.

Solution:

By formula,

Curved surface area = π * Length * ( Radius 1 + Radius 2 )

Here,

Length = √ ( Height + (  Radius 2 - Radius 1 )^2 )

Substituting,

√ ( 24 + ( 15 - 5 )^2 )

Length = 11 cm

Hence,

3.14 * 11 * ( 15 + 5 )

Curved surface area = 690 sq.cm