Question

A right-angled An ABC with sides 3 cm, 4 cm and 5 cm is revolved about the fixed side of 4 cm. Find the volume of the solid generated. Also, find the total surface area of the solid (V= 37.71cm^3, SA = 75.43cm^2)

Answer 1

Answer:

$\huge \fcolorbox{red}{lightblue}{\red{answer}}$

When rt. ∠ed △ABC is revolved about AB = 4 cm, it forms a right circular cone of radius 3 cm and height 4 cm . Slant height of the cone is 5 cm.

Volume of cone = 1 / 3 πr2h

1 / 3 × 22 / 7 × 3 × 3 × 4

= 37.71 cm3

Total surface area of the solid = πr2 + πrl = πr (r + l )

= 22 / 7 × 3 × 8 = 75.43 cm2

Answer 2

Answer:

When rt. ∠ed △ABC is revolved about AB = 4 cm, it forms a right circular cone of radius 3 cm and height 4 cm . Slant height of the cone is 5 cm.

Volume of cone = 1 / 3 πr2h

1 / 3 × 22 / 7 × 3 × 3 × 4

= 37.71 cm3

Total surface area of the solid = πr2 + πrl = πr (r + l )

= 22 / 7 × 3 × 8 = 75.43 cm2