“ Section 3 The lines on the sides of a plane are called edges, and the point at which they meet is called a vertex (lit. corner) .
Section 4 A plane is surrounded by not less than 3 edges. The type of shape of a plane is determined by its edges; if it has three edges it is called a triangle, if four a square, if five a pentagon and so on.
Section 5 According to the number of its edges is the number of its corners with the exception of a circle, which is enclosed with one line and has no corners. ”

“ The cube has length, width and height.
Section 2 The point, line and plane are not found in reality, though are connected to reality, as a plane is the side of a cube, the line is the side of a plane, and the point is the tip of a line. ”

“ Similarly, if you draw the circle FGI from the center C, the amount of degrees in arc FG from circle FGI is the same as the degrees in vertex ABC according to arc DE from circle DEH. In the same manner, whatever the distance of the arc that lies between the two lines, it remains in proportion to the circumference, and the angle is the same, regardless whether the length of the lines are in cubits, handbreaths, or finger measurements.
Section 10 A right angle is one that contains 90 degrees and whose edges are perpendicular, not leaning towards either side. ”