2. What are quadilaterals?
A quadrilateral is a polygon with
four sides (or 'edges') and four
vertices or corners.
3. WHAT ARE
POLYGONS?
In geometry a polygon is traditionally a
plane figure that is bounded by a closed
path or circuit, composed of a finite
sequence of straight line segments (i.e., by
a closed polygonal chain ). These segments
are called its edges or sides, and the
points where two edges meet are the
polygon's vertices (singular: vertex) or
corners.
4. HOW IS A
QUADRILATERAL A
POLYGON?
A quadrilateral is a polygon. In fact
it is a 4-sided polygon, just like a
triangle is a 3-sided polygon, a
pentagon is a 5-sided polygon, and so
on.
6. A line segment drawn from one vertex of a
quadrilateral to the opposite vertex is
called a diagonal of the quadrilateral. AC
is a diagonal of quadrilateral ABCD, as is
BD.
7. TYPES OF
QUADILATERALS
There are seven types of quadrilaterals
that can be divided into two groups:
parallelograms and other quadrilaterals.
Rectangle Trapezium
Rhombus
Square Parallelogram
10. COMPLEX
QUADILATERALS
When two sides cross over, you call it
a "Complex" or "Self-Intersecting"
quadrilateral like these:
They still have 4 sides, but two sides cross over.
11. ANGLE SUM OF A
QUADILATRAL
Draw a quadrilateral ABCD. Then
draw the diagonal AC to form two
triangles.
12. FINDING THE FOURTH
ANGLE OF A
QUADRILATERAL
If the measurements of three angles
of a quadrilateral are known, then
the missing angle can be calculated
13. ExampleFind the value of the pronumeral x in the
accompanying diagram. Give reasons for
your answer.
15. OTHER NAMES
A quadrilateral can sometimes be
called:
• A Quadrangle ("four angles"), so it
sounds like "triangle"
• A Tetragon ("four and polygon"), so
it sounds like "pentagon", "hexagon",
etc.
