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Consider a family of circles passing through two fixed points A(3,7)B(6,5). Find the point of concurrency of the chords in which the circle x^{2}+y^{2}-4x-6y-3=0 cuts the members of the family :

Option: 1

\left ( \frac{11}{17},\frac{3}{7} \right )
 


Option: 2

\left ( 2,\frac{23}{3}\right )

 


Option: 3

\left (-4,3\right )


Option: 4

chords are not concurrent


Answers (1)

best_answer

 

Equation of a circle in diametric form -

\left ( x-x_{1} \right )\left ( x-x_{2} \right )+\left ( y-y_{1} \right )\left ( y-y_{2} \right )= 0

 

- wherein

Where A\left ( x_{1},y_{1} \right )\, and \:B \left ( x_{2},y_{2} \right ) are the two diametric ends.

 

 

Family of circle -

S+KL= 0

- wherein

Equation of the family of circles passing through point of intersection S=0 \, and\, line\, L=0.

 

 

Equation of the family of circles passing through A(3,7) and B(6,5) is

(x-3)(x-6)+(y-7)(y-5)+\lambda (2x+3y-27)=0

Equation of given circle is x^{2}+y^{2}-4x-6y-3=0

\Rightarrow Equation of common chord is :-S_{1}-S_{2}=0

\Rightarrow (2\lambda -5)x+(3\lambda -6)y+(56-27\lambda )=0

\Rightarrow \lambda(2x+3y-27)-(5x+6y-56)=0

\Rightarrow This represents family of lies passing through the point of intersection of 2x+3y-27=0 & 5x+6y-56=0

\Rightarrow         fixed point =\left ( 2,\frac{23}{3} \right )

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manish

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