How did early mathematicians define trigonometric functions?

Answer:There are six trigonometric function, the first three are mainly used and other three are not use often, they are:Sine  (sin)Cosine  (cos)Tangent  (tan)Cosecant  (cosec or csc)Secant  (sec)Cotangent  (cot)They are mainly the ratio of two side of triangle.i.e. [tex]Sin x = \dfrac{Perpendicular}{Hypotenuse}[/tex][tex]Cos x = \dfrac{Base}{Hypotenuse}[/tex][tex]Tan x = \dfrac{Perpendicular}{Base}[/tex][tex]Cosec x = \dfrac{Hypotenuse}{Perpendicular}[/tex][tex]Sec x = \dfrac{Hypotenuse}{Base}[/tex][tex]Cot x = \dfrac{Base}{Perpendicular}[/tex]On the basis of these ratios there are different relations defined in Trigonometry Chapter.