AP EAMCET20224 Jul 2022Evening ShiftMathematicsApplication of DerivativesActual
Condition that 2 curves y 2 = 4 a x , x y = c 2 cut orthogonally is
Options
- Ac 2 = 16 a 2
- Bc 2 = 32 a 2
- Cc 4 = 16 a 4
- Dc 4 = 32 a 4
Correct answer
D. c 4 = 32 a 4
Step-by-step solution
Given y 2 = 4 a x ,   x y = c 2 For y 2 = 4 a x , 2 y d y d x = 4 a i.e. d y d x x 1 , y 1 = 2 a y 1 For x y = c 2 , x d y d x + y = 0 i.e. d y d x x 1 , y 1 = - y 1 x 1 For orthogonal intersection of both curves 2 a y 1 × - y 1 x 1 = - 1 i.e. x 1 = 2 a Also, y 1 2 = 4 a x 1 ⇒ y 1 2 = 8 a 2 and x 1 y 1 2 = c 2 2 ⇒ c 4 = 4 a 2 × 8 a 2 = 32 a 4