Question

A right angle triangle with sides 3 cm and 4 cm is revolved around its hypotenuse . Find the volume of the double cone thus generated.

Answer 1

`triangleAOB triangleABC`
`(AO)/(AB)=(OB)/(BC)=(AB)/(AC)`
`(R )/(4)=(3)/(5)rarr r=(12)/(5) cm`
`AC^(2)=AB^(2)+BC^(2)`
=9+16 =25
AC=5=`h_(1)+h_(2)`
Required area `=(1)/(3)pir^(2)+(1)/(3)pir^(2)h_(2)=(1)/(3)(h_(1)+h_(2))`
`=(1)/(3)xx(22)/(7)xx((12)/(5))^(2)xx5=30.17 cm^(3)`