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#1 2008-05-16 21:21:53
- Identity
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- Registered: 2007-04-18
- Posts: 934
Circle Theorems
Two circles intersect at A and B. The tangents at C and D intersect at T which is an extension of AB. If CBD is a straight line, prove that,
a) angle TAC = angle TAD
b) TC = TD
Thanks... I've been at this one for a long time
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#2 2008-05-16 23:30:35
- Kurre
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- Registered: 2006-07-18
- Posts: 280
Re: Circle Theorems
Hint: start by proving this theorem:
A circle and a point A is given. Let a line through A intersect the circle in points B and C, and draw a line PD, such that PD is a tangent to the circle with tangent point D. Then |AB|*|AC|=|AD|².
Your problem will follow quite easily from this theorem. 
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#3 2008-05-17 16:44:06
- Identity
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- Registered: 2007-04-18
- Posts: 934
Re: Circle Theorems
Wow! That theorem helped a lot Kurre 
In the meantime I had solved the problem by proving that ACDT is cyclic, but using that theorem it all comes together in a few simple steps!
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