UPSC 2014 CDS II Math Paper

Volume of the cone when triangle is revolved about longer leg
=‌‌

1

3

π×152×20
Volume of the cone when triangle is revolved about shorter leg
=‌‌

1

3

π×202×15
=‌‌

1

3

×3.14×202×15=6280cm3
Hence, statement 1 is incorrect. Volume of the cone when triangle is revolved about longer leg + Volume of the cone when triangle is revolved about shorter leg
=4710+6280=10990cm3
Volume of the double cone when triangle is revolved about the hypotenuse =3768cm3