Published by:
CGP EDU Academic Team
Published on: August 13, 2026
Prove that the circle x 2 + y 2 + 2ax + c 2 = 0 and x 2 + y 2 + 2by + c 2 = 0 touches each other
if 
Text Solution
Verified by ExpertsThe correct answer is:
CHECK THE SOLUTION.
Subtract to get common tangent and drop pependicular from centre on any one circle and equate it to its radius.
Radical axes is ax – by = 0 which touches both the circle
Now x 2 +
+ 2ax + c 2 = 0
⇒ (b 2 + a 2 )x 2 + 2ab 2 x + b 2 c 2 = 0
⇒ 4a 2 b 2 – 4(b 2 + a 2 ) b 2 c 2 = 0
⇒ a 2 b 2 = c 2 (b 2 + a 2 )
⇒
=
+ 
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