99 Percentile Qs Bank for JEE MainMathematicsDifferentiation
If x = 1 - t 2 1 + t 2 and y = 2 t 1 + t 2 , t h e n d y d x is equal to
Options
- A- y x
- By x
- C- x y
- Dx y
Correct answer
C. - x y
Step-by-step solution
∵ x = 1 - t 2 1 + t 2 a n d y = 2 t 1 + t 2 Put t = tan θ in both the equations, we get x = 1 - tan 2 θ 1 + tan 2 θ = cos 2 θ ...(i) and y = 2 tan θ 1 + tan 2 θ = sin 2 θ ...(ii) On differentiating both the eqs.(i) and (ii), we get d x d θ = - 2 sin 2 θ a n d d y d θ = 2 cos 2 θ Therefore, d y d x = d y d θ d x d θ = - cos 2 θ sin 2 θ = - x y