Circle And System Of Circles Question 50
Question: A circle with centre (a, b) passes through the origin. The equation of the tangent to the circle at the origin is
[RPET 2000]
Options:
A) $ y=-\frac{x}{m}\pm a\sqrt{1+m^{2}} $
B) $ x+my=\pm a\sqrt{1+m^{2}} $
C) $ x+my=\pm a\sqrt{1+{{(1/m)}^{2}}} $
D) $ x-my=\pm a\sqrt{1+m^{2}} $
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Answer:
Correct Answer: B
Solution:
Line perpendicular to $ y=mx+c $ is $ y=-\frac{1}{m}x+\lambda $ and $ m\lambda =\pm a\sqrt{1+m^{2}} $
Hence required tangent is $ my+x=\pm a\sqrt{1+m^{2}} $ .
BETA
