KVPY2010MathematicsApplication of Derivatives
Let V ₁ be the volume of a given right circular cone with O as the centre of the base and A as its apex. Let V ₂ be the maximum volume of the right circular cone inscribed in the given cone whose apex is O and whose base is parallel to the base of the given cone. Then the ratio V ₂ / V ₁ is-
Options
- A3 25
- B4 9
- C4 27
- D8 27
Correct answer
C. 4 27
Step-by-step solution
ABC and AOP are similar array c h r = H R h = rH R V ₂= 1 3 r ²( H - h )= 3 r ² H (1- r R )= H 3 ( r ³- r ³ R ) d V ₂ dr =2 r - 3 r ² R =0 r = 2 R 3 ~V _ 2 = 4 R ² H 81 array array l V ₁= R ² H 3 V ₂ ~V ₁ = 4 27 array