about三角比

This is the defination of Trigonometric functions,

can't tell you why.

We defined that:

sin=對bean/車bean

cos=鄰bean/車bean

and

tan=sin/cos



By the way, there are:

cot=1/tan

sec=1/cos

cosec=1/sin

係N年前d數學家出發明出黎

自己睇書= =
math書應該有...不過知黎無咩用