sec^2 = 1 + tan^2 or csc^2 = 1 + cot^2
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Originally Posted by reallylongnickname sec^2 = 1 + tan^2 or csc^2 = 1 + cot^2 Just divide the Pythagorean identity by cosine $\displaystyle \sin^2(x)+\cos^2(x)=1 \iff \frac{\sin^2(x)}{\cos^2(x)}+\frac{\cos^2(x)}{\cos^ 2(x)}=\frac{1}{\cos^2(x)}$ Now just simplify See if you can get other one
$\displaystyle csc^2(x) = 1 + cot^2(x)\longleftrightarrow \frac{1}{ sin^2(x)}-\frac{cos^2(x)}{sin^2(x)} = 1 $
Last edited by reallylongnickname; May 12th 2011 at 06:55 PM.
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