Circle And System Of Circles Question 230

Question: A circle is drawn to cut a chord of length 2a units along X-axis and to touch the Y-axis. The locus of the centre of the circle is

[Kerala (Engg.) 2005]

Options:

A) $ x^{2}+y^{2}=a^{2} $

B) $ x^{2}-y^{2}=a^{2} $

C) $ x+y=a^{2} $

D) $ x^{2}-y^{2}=4a^{2} $

E) $ x^{2}+y^{2}=4a^{2} $

Show Answer

Answer:

Correct Answer: B

Solution:

Since the perpendicular drawn on chord from $ O(x,y) $ bisects the chord. $ NM=a $

$ OM=y $

$ {{(ON)}^{2}}={{(OM)}^{2}}+{{(ON)}^{2}} $

$ x^{2}=y^{2}+a^{2} $

$ x^{2}-y^{2}=a^{2} $