8. From a solid cylinder whose height is 2.4 cm and diameter 1.4 cm, a

1.	8. From a solid cylinder whose height is 2.4 cm and diameter 1.4 cm, a conical cavity of thesame height and same diameter is hollowed out. Find the total surface area of theremaining solid to the nearest cm2
Answer» Given, Height of cylinder = Height of conicalcavity, h = 2.4 cm Diameter, d = 1.4 cm Radius, r = 1.4/2= 0.7 cm Slant height, l = √h² + r² = √(2.4)² + (0.7)² = √5.76 + 0.49 = √6.25 = 2.5 cm TSA of the remaining solid = CSA of cylindrical part + CSA of conical part+ Area of cylindrical base TSA = 2πrh+ πrl+ πr² = πr [ 2(h) + l + r ] = 22/7 × 0.7 [ 2 × 2.4 + 2.5 + 0.7 ] = 17.6 cm² Hence,TSA of remaining solid is = 17.6 cm²

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

Answer»

Given,

Height of cylinder = Height of conicalcavity, h = 2.4 cm

Diameter, d = 1.4 cm

Radius, r = 1.4/2= 0.7 cm

Slant height, l = √h² + r² = √(2.4)² + (0.7)² = √5.76 + 0.49 = √6.25 = 2.5 cm

TSA of the remaining solid = CSA of cylindrical part + CSA of conical part+ Area of cylindrical base

TSA = 2πrh+ πrl+ πr²

= πr [ 2(h) + l + r ]

= 22/7 × 0.7 [ 2 × 2.4 + 2.5 + 0.7 ]

= 17.6 cm²

Hence,TSA of remaining solid is = 17.6 cm²