DRAWING PLANE FIGURES
A plane has only two dimensions. Your layout is a
plane. This section gives methods of construction for
several plane figures.
DRAWING TRIANGLES WITH GIVEN
LENGTH SIDES
Figure 14-18 shows the steps in drawing a triangle
with given lengths for its sides. The lengths for the
Figure 14-19.--Drawing triangular plane figures. A. An
sides are shown in view A.
equilateral triangle. B. An isosceles triangle.
1. Draw one side of the triangle in the desired
position as the base line (view B).
perpendicular to a given line from a given point (refer
to fig. 14-9).
2. Adjust the dividers to the length of a second
side. Using one end of the base line as a center
CONSTRUCTING A REGULAR
for the point of the dividers, draw an arc (view
PENTAGON WITHIN A CIRCLE
B).
Look at figure 14-20. Here, you can see how to
3. Adjust the dividers to the length of the third side.
From the other end of the base line, draw another
draw a pentagon. Refer to figure 14-20 as you read the
arc that intersects the first arc (view B).
following section.
4. Draw lines from the intersection point of these
1. Draw the diameter of the circle, shown as line
arcs to the ends of the base line. They are for
AOB (view A).
the sides of the triangle (view C).
2. Bisect radius OB of the circle (view B).
DRAWING EQUILATERAL, ISOSCELES,
3. With D as a center and a radius equal to DC,
AND RIGHT TRIANGLES
strike arc CE (view C).
4. With C as a center, strike arc FG passing through
An equilateral triangle has three equal sides. To
point E (view D).
draw this type of triangle, first draw one side as the base
line. Then, use the length of that side as the radius to
5. Distance CF or CG is equal to the length of one
draw intersecting arcs from each end of the base line
side of the pentagon. Mark off the other sides
(fig. 14-19, view A).
with the dividers (view E).
An isosceles triangle has two equal sides. To draw
an isosceles triangle, first draw the base. Then, draw
intersecting arcs from each end of the base line. Use
the length of one of the equal sides as the radius (fig.
14-19, view B).
A right triangle has a 90-degree angle. You can
draw a right triangle by using the method for bisecting
a line (refer to fig. 14-2). Draw a perpendicular from
the end of a line (refer to fig. 14-8), or draw a
Figure 14-18.--Drawing a triangle with three given sides.
Figure 14-20.--Drawing a regular pentagon in a circle.
14-13
