You know what was my job? The Math tutor for the UB Alumni Student Althetes, their student numbers are the same like the CADS. They only do those math simple...

You should just memorize that purple....for all the sin, cos, tan, cot, sec, csc. There is only one way doing that, really. Its the same eternity defined triangle.

Right hand 3rd and the 4th finger with the thumb.

That is your memorized outlet, its still exactly the same 16 years in UB that video I made. You know how that Ms Congenality dropping a sandwitch on the paper? That is why I take that video off, because that piece of paper when I show you, has a stain. 

Want to do it? (The piano method)

All Right hand, 3rd finger = middle finger

Sin θ= 4th finger / 3rd finger

Cos θ=thumb / 3rd finger

Tan θ = 4th /  thumb

Reverse back

Cot θ= Thumb / 4th

Sec θ= 3rd / Thumb

Csc θ= 3rd / 4th

/ = division, how you say that in Math? You divide something. 

Your Sin θ = 4th finger divide to 3rd (Top 分子 / below 分母 )

分子 = numerator

分母 = denominator

I know the word denominator in English. There are a lot of things I learn when I was younger, they are in the formula sense, don't require to speak in the Chinese word coming out of your mouth, but those are Chinese I know how to describe to you.