Alright, I know I'm kind of shaky when it comes to proving elementary things rigorously.(adsbygoogle = window.adsbygoogle || []).push({});

I'm looking for for the most elementary (in the sense of using least possible mathematical knowledge) proof that

[tex] x < \tan x, {} {} \forall \frac{\pi}{2}>x>0 [/tex]

Geometrically ? I can't prove it... Algebraically ? How ? Using calculus ? I wish to see a proof to that, too...

You can also post links to freely available resources, if you know them.

EDIT: To make sense of post #2, the [itex] \pi/2 [/itex] was missing when ILS wrote his post.

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# Proof of an elementary but very important result

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