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Orthogonal trajectory for x^2 + y^2 =a^2(a is parameter) will be

  • Option 1)

    y^2 = cx

  • Option 2)

    y= cx^2

  • Option 3)

    y= cx

  • Option 4)

    y + x = c

 

Answers (1)

best_answer

As we have learnt,

 

Orthogonal Trajectory -

Any curve which cuts every member of a given family of curves at right angles

- wherein

 

 First of all we need defferential equation for given family of curves. So on differentiating we get,

2x +2y\frac{\mathrm{d} y}{\mathrm{d} x} = 0 \Rightarrow \frac{\mathrm{d} y} {\mathrm{d} x} = -\frac{x}{y}

Now, If replace \frac{\mathrm{d} y}{\mathrm{d} x} by -\frac{\mathrm{d} x}{\mathrm{d} y}, the obtained equation will be differential equation for required orthogonal trajectory.

So, we get

-\frac{\mathrm{d} x}{\mathrm{d} y} = -\frac{x}{y}\Rightarrow \frac{dx}{x} = \frac{dy}{y}

\Rightarrow On integrating we get

\ln x - \ln y = c\Rightarrow \frac{x}{y} = e^c \Rightarrow \frac{x}{y} = c \Rightarrow y = cx

 


Option 1)

y^2 = cx

Option 2)

y= cx^2

Option 3)

y= cx

Option 4)

y + x = c

Posted by

Himanshu

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