Get Answers to all your Questions

header-bg qa

A helicopter flying the curve given by y - x^{\frac{3}{2}} = 7, (x\geq 0). A soldier positioned at the point \left (\frac{1}{2}, 7 \right ) wants to shoot down the helicopter when its nearest to him. Then the nearest distance is:

  • Option 1)

    \frac{\sqrt5}{6}

  • Option 2)

    \frac{1}{6}\sqrt{\frac{7}{3}}

  • Option 3)

    \frac{1}{3}\sqrt{\frac{7}{3}}

  • Option 4)

    \frac{1}{2}

Answers (1)

best_answer

 

Equation of Normal -

Equation of normal to the curve  y = f(x) at the point  P(x1, y1) on the curve having a slope  MN  is 

(y-y_{1})=M_{N}(x-x_{1})


=\frac{-1}{\frac{dy}{dx}_{(x_{1},y_{1})}}(x-x_{1})

-

 

 

Length of Tangent -

L_{T}=\frac{y}{y'}\sqrt{1+y'^{2}}

- wherein

Where Where\:\:y'=\frac{dy}{dx}

 

Given equation of curve 

y-x^{\frac{3}{2}}=7 \: (x\geq 0)

from the concept 

\frac{dy}{dx}=\frac{3}{2}\sqrt x

condition for perpendicular of two line

=>(\frac{3}{2}\sqrt x)(\frac{7-4}{\frac{1}{2}-x})=-1

=>(\frac{3}{2}\sqrt x)(\frac{-x^{}\frac{3}{2}}{\frac{1}{2}-x})=-1

=>\frac{3}{2}x^{2}=\frac{1}{2}-x

=>3x^{2}+2x-1=0

=>(x+1)(3x-1)=0

x=-1\: \: is \: \: \: rejected \: \: \because x\geq 0

So,

x=\frac{1}{3}

y=7+(\frac{1}{3})^{\frac{3}{2}}

l_{AB}=\sqrt{(\frac{1}{2}-\frac{1}{3})^{2}}=\sqrt{\frac{1}{36}+\frac{1}{27}}=\frac{1}{6}\sqrt{\frac{7}{3}}

 

 


Option 1)

\frac{\sqrt5}{6}

Option 2)

\frac{1}{6}\sqrt{\frac{7}{3}}

Option 3)

\frac{1}{3}\sqrt{\frac{7}{3}}

Option 4)

\frac{1}{2}

Posted by

admin

View full answer

JEE Main high-scoring chapters and topics

Study 40% syllabus and score up to 100% marks in JEE