The radii of the top and bottom of a bucket

(a) Given, the radius of the top of the bucket, R = 28 cm

and the radius of the bottom of the bucket, r = 7 cm

Slant height of the bucket, l= 45 cm

Since, bucket is in the form of frustum of a cone.

∴  Curved surface area of the bucket = π l (R + r) = π x 45 (28 + 7)

$[\because$ curved surface area of frustum of a cone $=\pi(R+r) l]$

$=\pi \times 45 \times 35=\frac{22}{7} \times 45 \times 35=4950 \mathrm{~cm}^{2}$