56 CNC Machining
Quadrilaterals
A quadrilateral is a polygon with four sides, Figure 3-5. A line drawn
from one angle (intersecting corner) of a quadrilateral to the opposite angle
is called a diagonal.
Square
A square has four equal sides and four right (90°) angles. The opposite
sides of a square are parallel to each other. The diagonals of a square bisect
the four angles and each other. The diagonals are equal and perpendicular
to each other. The diagonals form congruent angles (equal in size and
shape).
Rectangle
A rectangle is a quadrilateral with equal opposite sides and four right
angles. The opposite sides are parallel to each other. The diagonals are
equal, bisect each other, and create two pairs of congruent triangles.
Right
Equilateral
Isosceles
Scalene
K K
H
H H L
N
M
Figure 3-4. Examples of various types of triangles. The sum of the angles in a triangle always equals
180°.