Triangle Formulas

[mathpimp]

I always forget those triangle formulas and trig identities from the old days of Precal/Trig...

So I say we write some of them down here, you guys can tell me what I'm forgetting.

Heron's Formula- three side lengths known.

[unparseable or potentially dangerous latex formula]

[unparseable or potentially dangerous latex formula]

[mathpimp]

Trig Identities:

[unparseable or potentially dangerous latex formula]

Wow I'm brain dead. Help please.

[stupidityismygam]

[unparseable or potentially dangerous latex formula] where [unparseable or potentially dangerous latex formula] is the area, [unparseable or potentially dangerous latex formula] is the semiperimeter, and [unparseable or potentially dangerous latex formula] is the inradius

[unparseable or potentially dangerous latex formula] where [unparseable or potentially dangerous latex formula] is the circumradius (follows from the below)

[unparseable or potentially dangerous latex formula]

[unparseable or potentially dangerous latex formula]

[unparseable or potentially dangerous latex formula]

thats all i can think of right now

[stupidityismygam]

[Kurt]

For a triangle ABC,

[unparseable or potentially dangerous latex formula]

[unparseable or potentially dangerous latex formula]

Also if a circle is inscribed/circumscribed, then

[unparseable or potentially dangerous latex formula] (for s being the semiperimeter)
[unparseable or potentially dangerous latex formula]

And just for kicks, [unparseable or potentially dangerous latex formula]

Those are mostly used on calculator tests though. And unfortunately UIL does nothing with excircles, Ceva's, etc.