Drawing arc in Turbo Pascal

I am using TP for step motor control. Each motion of the motors is
shown on the monitor. So I am using command "linerel(1,0)" for +x
axis and "linerel(0,-1)" for -y axis.
My question is, how can I draw an arc by using linerel command. For
example arc(300,300,0,270,100) means 300,300 is the center point of
the arc, 0 is the start angle and 270 is the final angle, and 100 is
the radius.
I mean first I should sat moveto(300,300) and than linerel(...)??!?!