Question
The equation of circles passing through (3, _6) touching both the axes is
Options
##A#
##S#
Now
(r _ 3)2 + (_r + 6)2 = r2
r2 _ 18r + 45 = 0
Þ r = 3, 15
Hence circle
(x _ 3)2 + (y + 3)2 = 32
x2 + y2 _ 6x + 6y + 9 = 0
(x _ 15)2 + (y + 15)2 = (15)2
Þ x2 + y2 _ 30x + 30y + 225 = 0
The equation of circles passing through (3, _6) touching both the axes is
(#oA) x2 + y2 _ 6x + 6y + 9 = 0 (#oB) x2 + y2 + 6x _ 6y + 9 = 0
(#oC) x2 + y2 + 30x _ 30y + 225 = 0 (#oD*) x2 + y2 _ 30x + 30y + 225 = 0
Solution
Now
(r _ 3)2 + (_r + 6)2 = r2
r2 _ 18r + 45 = 0
Þ r = 3, 15
Hence circle
(x _ 3)2 + (y + 3)2 = 32
x2 + y2 _ 6x + 6y + 9 = 0
(x _ 15)2 + (y + 15)2 = (15)2
Þ x2 + y2 _ 30x + 30y + 225 = 0
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