I'm in calc 2 and don't really remember much from trig (took it in highschool 3 years ago and my act was so high I skipped college math through calc 1, going strait into calc2). I just need all the basics in one place -- not a lesson (I remember all the basics/principles) just the identities and stuff. Especially the special angles like sin(pi/4)=1/sqrt(2) and the special triangles you use to get these angles.

 

I remember a friend of mine used to have a sheet like this he found on the Internet that was meant specifically to be a reference (but a general website is all I really need).

What I always use...

 

http://en.wikipedia.org/wiki/List_of_trigonometric_identities

 

But a google for:

 

trigonometric identities

 

Give lots of options...

Although my course books catered for everything I needed, I used Wolfram and just wordpad to build a more extensive list, that way you can add notes and compare identities and formulas, plus you can create a reference sheet exactly how you want it.

I remember a friend of mine used to have a sheet like this he found on the Internet that was meant specifically to be a reference (but a general website is all I really need).

 

 

http://mathworld.wolfram.com/

The very first things you need to know are:

 

[math]sin^2\alpha + co^2\alpha = 1[/math]

 

[math]tg\alpha = \frac{sin\alpha}{cos\alpha}[/math]

 

[math]ctg\alpha = \frac{cos\alpha}{sin\alpha}[/math]

 

[math]sin\alpha = \frac{tg\alpha}{\sqrt{tg^2\alpha + 1}}[/math]

 

[math]cos\alpha = \frac{1}{\sqrt{tg^2\alpha + 1}}[/math]

 

[math]sin\alpha = \frac{1}{\sqrt{ctg^2\alpha + 1}}[/math]

 

[math]cos\alpha = \frac{ctg\alpha}{\sqrt{ctg^2\alpha + 1}}[/math]

 

[math]sin2\alpha = 2sin\alpha cos\alpha[/math]

 

[math]cos2\alpha = con^2\alpha - sin^2\alpha[/math]

 

[math]tg2\alpha = \frac{2tg\alpha}{1 - tg^2\alpha}[/math]

 

[math]ctg2\alpha = \frac{ctg^2\alpha - 1}{2ctg\alpha}[/math]

 

[math]sin(\alpha \pm \beta) = sin\alpha cos\beta \pm cos\alpha sin\beta[/math]

 

[math]cos(\alpha \pm \beta) = cos\alpha cos\beta \mp sin\alpha cos\beta[/math]

 

[math]tg(\alpha \pm \beta) = \frac{tg\alpha \pm tg\beta}{1 \mp tg\alpha tg\beta}[/math]

 

[math]ctg(\alpha \pm \beta) = \frac{1 \mp ctg\alpha ctg\beta}{crt\alpha \pm ctg\beta}[/math]

 

These are the key ones!

 

Cheers,

Shade

Shade

 

You might want to use the \sin and \cos terms in LaTeX in your equations there, without them, all the text runs together and is very hard to read

 

e.g.

 

[math] \sin^2{\alpha} + \cos^2{\alpha} = 1[/math]

 

or

 

[math] \cot{\alpha} = \frac{\cos{\alpha}}{\sin{\alpha}}[/math]

 

the trig functions are written in a more upright script and there is a space between "sin" and "alpha" that is much easier to read. It gets really hard to read the angle sum and difference equations, for example.

 

[math] \sin{(\alpha \pm \beta)} = \sin{\alpha}\cos{\beta} \pm \sin{\beta}\cos{\alpha} [/math]

Oh, I didn't know there were sin and cos in LaTeX too!

Sorry but I hope you understand this time (although I can see them without problem)

 

Thanks for letting me know Bignose!

 

Cheers,

Shade