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#1 2007-01-17 05:02:26

soha
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Registered: 2006-07-07
Posts: 2,530

Whats X

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#2 2007-01-17 05:10:16

Toast
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Registered: 2006-10-08
Posts: 1,321

Re: Whats X

Well, I forgot how to prove this, but if a triangle resides in a circle so that one of its sides is the diameter and all vertices rest on the circumference, then the angle opposite the diameter will always be 90 degrees.
So, in BDC, since BD is the diameter, angle C must be 90 degrees.

Let's call the complementary angle of x 'y'. Angle y is part of Triangle ABC. Since AC is the diameter, angle B must equal 90 degrees. Hence, angle y = 180-45-90=45 degrees.

As y is complementary to x (y+x=90), x = 90-45 = 45 degrees.

Last edited by Toast (2007-01-17 05:17:04)

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