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You are not logged in. #1 20131125 23:16:58
Tangents to 2 circles'The circle S1 with centre C1(a1, b1) and radius r1 touches externally the circle S2 with centre C2(a2, b2) and radius r2. The tangent at their common point passes through the origin. Show that #2 20131126 00:46:10
Re: Tangents to 2 circleshi jimi70 That may help. FURTHER EDIT: I haven't done it yet but I'm still trying ...................... Bob Last edited by bob bundy (20131126 01:27:47) You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei #4 20131126 04:30:58
Re: Tangents to 2 circles
Let be the point of contact of the circles. The tangent through this point is perpendicular to the line joining their circles, which has gradient ; therefore the tangent through the common point has gradient . In other words, the point lies on the line : The equations of the circles are and ; since lies on both of them Now subtract [3] from [2] and use the relation [1], and you should get the answer. 134 books currently added on Goodreads #7 20131126 11:57:39
Re: Tangents to 2 circlesHe's probably asking because the OP has stated that it is the second part he is not able to do. The limit operator is just an excuse for doing something you know you can't. “It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman “Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment #8 20131126 19:48:35
Re: Tangents to 2 circleshi Nehushtan
I did and it left me very confused. You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei 