Question

30 circular plates, each of radius 14 cm and thickness 3 cm are placed one above the another to form a cylindrical solid. Find the total surface area.

Answer 1

Given, radius of a circular plate, r = 14 cm

Thickness of a circular plate = 3 cm

Thickness of 30 circular plates = 30 × 3 = 90 cm

Since, 30 circular plates are placed one above the another to form a cylindrical solid.

Then, Height of the cylindrical solid, h = Thickness of 30 circular plates = 90 cm

Total surface area of the cylindrical solid so formed

= `2πr(h + r) = 2 xx (22/7) xx 14(90 + 14)`

= 44 × 2 × 104

= 9152 cm²

Hence, the total surface area of the cylindrical solid is 9152 cm².