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Topic: Trapazoid geometry
Replies: 2   Last Post: Jul 8, 2008 5:37 AM

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Peter Chang

Posts: 8
From: new zealand
Registered: 7/5/08
Re: Trapazoid geometry
Posted: Jul 8, 2008 5:37 AM
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Suppose that AB//CD, the other two sides that are not parallel are BC and AD,
Let alpha and beta denote the angle <ADC and <BCD.
Let a , b and h denote AB, CD and the trapezoid altitude.

Draw line BE // AD.

In triangle BCE,
h/tan(alpha) + h/tan(beta) = b - a

h = (b - a)/[1/tan(alpha) + 1/tan(beta)]
= (b - a)tan(alpha)tan(beta)/[tan(alpha) + tan(beta)]

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