The importance of this research lies in notifying analytic
geometry principles in Lobachevsky plane which differ from
the famous principles in Euclidean plane .
In this research, length of curves with constant curvature ,
length of a circle and a
n arc length of it opp to a central angle
has been found . Moreover , it has been reached to a formula
to express the distance between two points ; then writing a
line equation passes coordinates principle , a line equation that
doesn`t pass coordinates principle and a circle equation. We
coordinates which have used for that Beltrami
made the formulas simpler.
