Talk:Law of tangents

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Can someone improve this page, it is too short and confusing


Certainly this can be expanded. Maybe tomorrow.... Michael Hardy 21:54, 27 May 2006 (UTC)
--shenron 00:38, 15 January 2007 (UTC) More changes, I added the Example Section and changed a couple of minor things in the introduction. I added a little bit about why it's usefull, but there still needs to be information about how it was discovered
--shenron 23:01, 14 January 2007 (UTC) I added a proof to the page today from http://planetmath.org/encyclopedia/ProofOfTangentsLaw.html

[edit] Expansion

I think it would be nice if someone would expand the page by explaining something the law is used for. Perhaps why it was formulated to begin with. If neither of these apply, perhaps indicating this would help.

[edit] error in example

This article says:

{{-\tan{\alpha + 60 \over 2}}} = {5}{\tan{\alpha - 60 \over 2}}.
Take the inverse tangent of both sides:
{-\left({\alpha + 60 \over 2}\right)} = {{5}\left({\alpha - 60 \over 2}\right)}.

This is a gross error. Taking the inverse tangent of both sides would yield

{-\left({\alpha + 60 \over 2}\right)} = \arctan\left( 5 \tan\left({\alpha - 60 \over 2}\right)\right).

Somehow this got changed to

{-\left({\alpha + 60 \over 2}\right)} = 5 \arctan\left( \tan\left({\alpha - 60 \over 2}\right)\right),

so that "arctan" and "tan" cancel to give

{-\left({\alpha + 60 \over 2}\right)} = {{5}\left({\alpha - 60 \over 2}\right)}.

That certainly is not correct. Michael Hardy 02:14, 30 January 2007 (UTC)

... and now I've deleted that section. Michael Hardy 02:16, 30 January 2007 (UTC)

This can be prooved without all of these unnecessary equations. Check out this website, you'll be able to figure out in your own ,mind how to think about these things without having to memorize the unnecessry equations, and then be able to figure out where the equations came from. —Preceding unsigned comment added by 70.192.58.16 (talk • contribs)