Sine, Cosine, and Tangent on a Circle
Date: 04/14/99 at 00:02:55 From: Willy Jongejan Subject: The relation of sine, cosine, and tangent to a circle This should be easy for you, but I'm stuck. Do you have any visuals of where the sine, cosine, and tangent are on a unit circle? Thanks.
Date: 04/14/99 at 09:10:43 From: Doctor Rob Subject: Re: The relation of sine, cosine, and tangent to a circle Q _..-----.._ .+' `-. ,' |\ `. ,' | \ `. / | \1 \ / | \ \ . sin(x)| \ . | | \ x 1 | +-------+------+--------------+ P | R cos(x) \O | . \ . \ \ /| \ \ / | `. \ ,' | `. \ .' | `-._ _.-' | ''-----'' \ |tan(x) \ | x = <POQ, sec(x)\ | |sin(x)| = length(RQ), \ | |cos(x)| = length(OR), \ | |tan(x)| = length(PS), \ | |sec(x)| = length(OS). \| o S The signs of each are determined by which quadrant x falls in. If x is in the first quadrant, then all are positive. In this picture, x is in the second quadrant so the sine is positive and the rest negative. - Doctor Rob, The Math Forum http://mathforum.org/dr.math/
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