A) 5
B) \[2\sqrt{5}\]
C) 4
D) \[\sqrt{57}\]
Correct Answer: A
Solution :
Circle C \[{{S}_{1}}+\lambda {{S}_{2}}\,=\,O\] \[{{x}^{2}}+{{y}^{2}}+4x-6y-12+\lambda ({{(x-1)}^{2}}+{{(y+1)}^{2}})=0\] it passes through (4, 0) \[16+0+16-0-12+\lambda (9+1)=0\] \[\lambda =-2\] \[{{x}^{2}}+{{y}^{2}}+4x-6y-12-2\left( {{x}^{2}}+{{y}^{2}}-2x+2y+2 \right)\] = 0 \[{{x}^{2}}+{{y}^{2}}-8x+10y+16=0\] \[r=\sqrt{6+25-16}\,\,=\,5\]You need to login to perform this action.
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