From the diagram:
A quadrilateral with its diagonals is shown. The top vertex is labeled as $A$A. The bottom vertex is labeled as $C$C. The right vertex is labeled as $D$D. The left vertex is labeled as $B$B. A vertical dashed line connects vertex $A$A to vertex $C$C, forming diagonal $AC$AC. A horizontal solid line connects vertex $B$B to vertex $D$D, forming diagonal $BD$BD. Diagonals $AC$AC and $BD$BD intersect at point $E$E, forming segments $BE$BE and $ED$ED. Both segments $BE$BE and $ED$ED are marked with double tick marks.
What can be said about point E?
It is the midpoint of the segment $BD$BD.
It is equidistant from A and C.
Using the diagram shown, find the length $PR$PR.
Know precise definitions of angle, circle, perpendicular line, parallel line, and line segment, based on the undefined notions of point, line, distance along a line, and distance around a circular arc.