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The number of common tangents to the circles x^{2}+y^{2}-4x-6y-12=0\, and\, x^{2}+y^{2}+6x+18y+26=0,is:

  • Option 1)

    1

  • Option 2)

    2

  • Option 3)

    3

  • Option 4)

    4

 

Answers (2)

best_answer

 

Common tangents of two circles -

When two circles touch  each other externally, there are three common tangents, two of them are direct.

 

- wherein

 

 C_1=(2,3)

C_2=(-3,-9)

C_1C_2=\sqrt{25+144}

r_1=\sqrt{4+9+12}= 5

r_2=\sqrt{9+81-26}= 8

\therefore r_1+r_2=C_1C_2

 

3 Tangents for circle touching externally


Option 1)

1

Option 2)

2

Option 3)

3

Option 4)

4

Posted by

Plabita

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