Circle And System Of Circles Question 51
Question: The two circles $ x^{2}+y^{2}-2x+6y+6=0 $ and $ x^{2}+y^{2}-5x+6y+15=0 $ touch each other. The equation of their common tangent is
[DCE 1999]
Options:
A) $ ax-by=0 $
B) $ ax+by=0 $
C) $ bx-ay=0 $
D) $ bx+ay=0 $
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Answer:
Correct Answer: B
Solution:
Obviously the slope of the tangent will be $ -( \frac{1}{b/a} ) $ i.e., $ -\frac{a}{b} $ .
Hence the equation of the tangent is $ y=-\frac{a}{b}x\ $ i.e., $ by+ax=0 $ .
BETA
