side is anti-clockwise.
side is clockwise.
is defined as the angle subtended at the centre of a circle by an arc whose length is
equal to the radius.
below:
The figure obtained by rotating a given ray about its end point is called an angle.
An angle is called positive if the direction of rotation of ray from initial side to terminal
An angle is called negative if the direction of rotation of ray from initial side to terminal
Sexagesimal system 
Circular system
180o = p radians .
The positive and negative sign of t-ratios of
below:
