CircleHard
Question
If the two circles, x2 + y2 + 2g1x + 2f1y = 0 and x2 + y2 + 2g2x + 2f2y = 0 touches each other, then -
Options
A.f1g1 = f2g2
B.
C.f1f2 = g1g2
D.none
Solution
C1C2 = r1 + r2
⇒ (g1 - g2)2 + (f1 - f2)2 =
⇒ -2g1g2 - 2f1f2 = ± 2
⇒ g1f2 - g2f1 = 0
⇒
⇒ (g1 - g2)2 + (f1 - f2)2 =
⇒ -2g1g2 - 2f1f2 = ± 2
⇒ g1f2 - g2f1 = 0
⇒
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