Question

From a solid cylinder whose height is 2.4 cm and diameter 1.4 cm, a conical cavity of the same height and same diameter is hollowed out. Find the total surface area of the remaining solid to the nearest cm².

Answer 1

Height of the cylinder, h = 2.4 m. 

Diameter of the cylinder, d = 1.4 m. 

∴ Radius, r = 0.7 m. 

(i) Outer Curved surface area of cylinder = 2πrh

= 44. × 0.24 = 10.56 cm² . 

(ii) Area of base of = πr²

(iii) Inner surface area of cylinder, = πrl

= 5.5 cm² 

∴ Total surface area of newly formed cube = 10.56 + 1.54 + 5.5 = 17.6 cm² . 

∴ Nearest value is 18 sq.cm.