A right circular cylinder has height 21cm and radius 7cm. The cylinder is cut into three equal parts parallel to the base. What is the increase in total surface area?

616 cm²

T.S.A. of bigger cylinder = 2\(\pi \)rH + 2\(\pi \)r²........(i)

T.S.A. of 3 parts = 3 × (2\(\pi \)rh + 2\(\pi \)r²)

                        = 2\(\pi \)rH + 6\(\pi \)r² ..........(ii)          (∵3h = H) 

⇒ Increase is (ii) - (i),

⇒ 4\(\pi \)r² = 4 × \(\frac{22}{7}\) × 7 × 7 = 616 cm²