AP EAMCET202018 Sep 2020Evening ShiftMathematicsCircleActual
Find the minimum radius of the circle which is orthogonal to both the circles (x^2+y^2+4 x+3=0 ) and (x^2+y^2-12 x+35=0 ).
Options
- A1
- B4
- C( 17 )
- D( 15 )
Correct answer
D. ( 15 )
Step-by-step solution
Centre of circle cuts the circles ( aligned S₁: x^2+y^2+4 x+3 & =0 S₂: x^2+y^2-12 x+35 & =0 aligned ) Radical Axis is (S₁-S₂=0 x=2 ) and ((2,0) ) lies on the line segment joining centres of circles (S₁ ) and (S₂ ) Minimum radius (= ) length of tangent from ((2,0) ) ( to circle aligned S₁ & =0 (or) S₂=0 & = 4+8+3 = 15 aligned ) Hence, option (d) is correct.