Polygonal Construction, Continued
Triangles
The preferred method of drawing triangles is with triangles or a protractor.
To draw triangles using triangles, use this table:
Step
Action
1
Select a triangle that contains the angles required to draw the
triangle. For example, select a 30/60/90° triangle to draw an
equilateral triangle where each angle equals 60°.
2
Draw a perpendicular line to the center of AB.
2
With given horizontal line AB, place the triangle base edge against
the straightedge of your drafting table with the 60° angle at A.
3
Draw line AC to the perpendicular line.
4
Flip the triangle over to place the 60° angle at the base of the
triangle at B and against the straightedge of your table.
5
Draw line BC. Lines AC and BC should intersect above the center
of line AB and form a 60° angle to complete the equilateral triangle.
Figure 2-37 shows the construction of an equilateral triangle using a
30°/60°/90° triangle.
Figure 2-37.—Constructing an equilateral triangle.
Continued on next page
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