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Let C_{1}\: \: and\: \: C_{2} be the centres  of the circles x^{2}+y^{2}-2x-2y-2=0 and x^{2}+y^{2}-6x-6y+14=0 respectively. If P and Q are the points of intersection of these circles, then the area (in sq. units) of the quadrilateral PC_{1}QC_{2} is : 

  • Option 1)

    8

  • Option 2)

    4

  • Option 3)

    9

  • Option 4)

    6

Answers (1)

best_answer

@5089

General form of a circle -

x^{2}+y^{2}+2gx+2fy+c= 0
 

- wherein

centre = \left ( -g,-f \right )

radius = \sqrt{g^{2}+f^{2}-c}

 

 

Common tangents of two circle -

When they intersect, there are two common tangents, both of them being direct.

|r_1-r_2|<\left|C_1C_2\right|<r_1+r_2

- wherein

Equation of circle with centre C_{1}(1,1)

(x-1)^{2}+(y-1)^{2}=4

 Equation of circle with centre C_{2}(3,3)

(x-3)^{2}+(y-3)^{2}=4

Two circles are orthogonal , 

Hence , 

Area = 2(\frac{1}{2}\cdot 2\cdot 2)=4 \: sq. units

 

 

 


Option 1)

8

Option 2)

4

Option 3)

9

Option 4)

6

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