Given: slant height of bucket = l = 45 cm

Radius of bottom circle = r = 7 cm

Radius of top circle = R = 28 cm

As the bucket is in the form of frustum

Formula: Total surface area of frustum = πr² + πR² + π(R + r)l cm²

Now we have asked curved surface area, so we should subtract the top and bottom surface

areas which are flat circles.

Surface area of top = πr²

Surface area of bottom = πR²

∴ Curved surface area = total surface area – πr² - πR² cm²

= πr² + πR² + π(R + r)l – πr² - πR² cm²

= π(R + r)l cm²

= 3.14 × (28 + 7) × 45 cm²

= 3.14 × 35 × 45 cm²

= 4945.5 cm²

Therefore, curved surface area of bucket = 4945.5 cm²