trigonometric curve


Literally trigonometry does mean the measurement of angles1). Euler was the first who defined (1749) the trigonometric functions as proportions of lines. He was also the one who introduced the notation for these functions.
But long for the starting of the era scholars in the old Greece and in India where already studying the trigonometric functions. In the Middle Ages (800 AD) the functions have been studied intensively by Arab speaking mathematicians. All used the functions as cords, it took until the 18th century that the current view was adopted.

The basic trigonometric functions are:

Some more advanced trigonometric functions are :


1) goonia (Gr.) = angle, metreoo (Gr.) = to measure