Question

please solve this question friends friends friends class 10 maths board exam board exam board exam

Answer 1

 
In the right angled triangle ABC (right angled at B) 
AB= 4cm and BC= 3cm 

AC= square root 3 square + 4 square  = Square root 9+16 = Square root 25 = 5cm 

Area of triangle ABC = ½ ABxBC = ½ ACxBO 

ABxBC = ACxBO 
4x3 = 5xBO 

BO= 12/5 = 2.4cm 
The volume of the required double cone = volume of the cone ABD + volume of the cone BCD = 1/3 pi r square h1 + 1/3 pi r square h square [where h1 and h2 are the heights of the cone ABD and BCD respectively] 

Surface area of double cone = surface area of cone ABD + surface area of cone BCD 
Pi r l1 + pi r l2 
Pi r (l1 + l2) 

22/7 x 2.4 x (4+3) 

22/7 x 2.4 x 7 

= 52.8 cm square 

So the volume of double cone is 30.17 cubic cm and surface area of double cone is 52.8 sq cm