Mathematics for Carpenters and Builders - Carpenter's and Builder's Math, Plans, and Specifications - page 154

In Figure 5-27, assuming line AB is to be divided into five equal
parts, draw a diagonal line AC of five units in length. Join BC at 5
and through the points 1, 2, 3, and 4. Draw lines 1 L ,2 a , and so
forth, parallel to BC. AC will then be divided into five equal parts,
AL, La, ar, rf , and fB .

L a r f

B

A

1

2

3

4

C

5

Figure 5-27 To divide a line into a number of equal parts.

Problem 7
To draw an angle equal to a given angle on a straight line.
In Figure 5-28, let A be the given angle, and FG the line. With any
radius from the points A and F , describe arcs DE and IH cutting
the sides of angle A and line FG . Lay off arc IH equal to arc DE ,
and draw line FH . Angle F is then equal to A , as required

C

E H

B F G

A

D

Figure 5-28 To draw an angle equal to a given angle on a

straight line.

Problem 8
To bisect an angle
In Figure 5-29, let ACB be the angle. With the center of the angle
at C , describe an arc cutting the sides at A and B . Using A and B
as centers, describe arcs that intersect at D . A line through C and
D will divide the angle into two equal parts.
Problem 9
To find the center of a circle.