54 CNC Machining
• Bisect. To divide into two equal parts.
• Congruent. Having the same size and shape.
• Diagonal. Running from one corner of a four-sided figure to the
opposite corner.
• Parallel. Lying in the same direction but always the same distance apart.
• Perpendicular. At a right angle to a line or surface.
• Segment. That part of a straight line included between two points.
• Tangent. A line contacting a circle at one point.
• Transversal. A line that intersects two or more lines.
Angles
An angle (∠) is the figure formed by the meeting of two lines at the
same point or origin called the vertex. See Figure 3-1. Angles are measured
in degrees (°), minutes (′), and seconds (″). A degree is equal to 1/360 of a
circle, a minute is equal to 1/60 of 1°, and a second is equal to 1/60 of 1′.
There are many types of angles, Figure 3-2. An acute angle is greater
than 0° and less than 90°. An obtuse angle is greater than 90° and less
than 180°. A right angle is exactly 90°. A straight angle is exactly 180°, or a
straight line. A reflex angle is greater than 180° and less than 360°.
An angle can also be described by its relationship to another angle.
See Figure 3-3. Adjacent angles are two angles that use a common side.
Complementary angles are two angles that equal 90°. Supplementary
angles are two angles that equal 180°, or a straight line.
Polygons
Polygons are figures with many sides that are formed by line segments.
Polygons are named according to the number of sides and angles they have.
For example, a decagon is a polygon with ten sides; deca comes from the
Latin word for ten.
Triangles
A triangle is a three-sided polygon. There are a number of types of
triangles, Figure 3-4. A right triangle has a 90° (right) angle. An isosceles
triangle has two equal sides and two equal angles. An equilateral triangle
has three equal sides; all angles are equal (60°). A scalene triangle has
three unequal sides and unequal angles.
Figure 3-1. Angle defined as EFG.
Vertex
F
E
G
30°