29. A Rectangle is a Parallelogram whose angles are all right angles.

30. A Rhomboid is a Parallelogram whose angles are not right angles.

31. All other four fided figures are called Trapeziums.

32. A Line drawn from one angle of a figure to another is called the Diagonal.

33. All figures contained by more than four fides are called Polygons.

34. All Regular Polygons are named according to the number of lines they are contained by:

Trigon

Tetragon

To divide a given line AB into two equal parts.

On the centre B with any radius greater than half the line, defcribe the arc a a.

With the fame radius, and A as a centre, describe the arc bb.

Through the points of interfection draw the line CD, which will divide the given line into two equal parts.

N. B. ED is a perpendicular raised in the middle of the line A B.

PROBLEM II.

To erect a perpendicular from a given point C in a given right line A B.

A

B

a

C

b

When the given point is near the middle of the line, fet off two equal distances from it on the line A B, as C a and C b.

With any radius greater than a C, and a as a centre, -defcribe an arc.

With the fame radius, and b as a centre, describe another arc cutting the former in D.

Draw the line CD, which will be the perpendicular required