32. What are meant by the medians of a triangle?
33. What is meant by the third diagonal of a quadrilateral?
34. Mention some propositions in Book I. which are particular cases of more general ones that follow.
35. What is the sum of all the exterior angles of any rectilineal figure equal to?
36. How many conditions must be given in order to construct a triangle? Ans. Three; such as the three sides, or two sides and an angle, &c.
Exercises on Book I.
1. Any triangle is equal to the fourth part of that which is formed by drawing through each vertex a line parallel to its opposite side.
2. The three perpendiculars of the first triangle in question 1 are the perpendiculars at the middle points of the sides of the second triangle.
3. Through a given point draw a line so that the portion intercepted by the legs of a given angle may be bisected in the point.
4. The three medians of a triangle are concurrent.