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Assume I have a trapezoid and I know all its sides:

$AB = 10$

$CD =6$

$AC = 3$

$BD = 5$

I need to know the angle between $AB$ and $AC$.

AB and CD are parallel

user844541
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  • There are really a lot of open ends to this question concerning which pair is parallel and the relative positions of the parallel sides. Several (all?) of these might be eliminated by doing cases, but I just want to make sure you've really supplied all the information you've been given. I can tell you one such trapezoid, but I haven't bothered to wade through the cases to see if there are more. – rschwieb Mar 11 '13 at 18:50

1 Answers1

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I assume that $AB\parallel CD$. Then the line parallel to $BD$ passing through $C$ intersects $AB$ in a point $P$ such that we know the lengths of all sides in triangle $APC$ as $AP=10-6=4, PC=BD=5, CA=3$.

Hagen von Eitzen
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