### Saccheri quadrilaterals; Lambert quadrilaterals

Draw a diagram of a Saccheri quadrilateral ABDC, where (a) A and B are a pair of consecutive vertices (b) sides AD and BC are a pair of opposite sides (c) angles A and B are right angles (d) sides AD and BC are congruent. Then let M be the midpoint of AB, and drop a perpendicular from M to CD with foot N. Once