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Equation of curve passing through (2,2) such that subtangent and subnormal at any point of it are equal is

  • Option 1)

    y = -x

  • Option 2)

    y + x =2

  • Option 3)

    y = x

  • Option 4)

    y + x =3

 

Answers (1)

best_answer

As we have learnt,

 

Subnormal -

Length =y\tan\alpha = y\frac{dy}{dx}

- wherein

 

 Subnormal= y\frac{\mathrm{d} y}{\mathrm{d} x} and subtangent = y\frac{\mathrm{d} x}{\mathrm{d} y}

According to question -

y\frac{\mathrm{d} x}{\mathrm{d} y} = y\frac{\mathrm{d} y}{\mathrm{d} x}\Rightarrow\left ( \frac{\mathrm{d} y}{\mathrm{d} x} \right)^2= 1

\\*\Rightarrow \frac{\mathrm{d} y}{\mathrm{d} x} = 1 \; or\; -1 \\*\Rightarrow y = x+ c\;or\; y = -x + c \\*\Rightarrow x-y = c\;or\;x+y = c

But the curve passes through (2,2) so they must satisfy hence, curves are either y = x or x+ y = 4

 


Option 1)

y = -x

Option 2)

y + x =2

Option 3)

y = x

Option 4)

y + x =3

Posted by

Himanshu

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