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by Carol Edelstein
Polygon – a closed, straight-sided, plane figure.
Angle – two rays that meet at a common end point.
Degree – a unit of measurement of an angle, represented by the symbol º.
90º
Diagonal – a line segment joining two non-adjacent vertices of a polygon.
Quadrilateral – a polygon with 4 angles and 4 straight sides.
Parallelograms – opposite sides are parallel and congruent.
• Rectangles – a parallelogram with all angles
90°.
• Squares – a rectangle with all sides equal .
• Rhombus – a parallelogram with all sides equal.
Trapezoid – one set of sides are parallel.
Quadrilaterals – 4 sided polygon
Parallelograms (opposite sides are parallel and congruent).
Trapezoids (one set of parallel sides)
Square
Rectangle
Rhombus
parallelogram rectangle
rhombus square
trapezoid
quadrilateral
The sum of all the interior angles equals 360º.
Why is the sum 360º ? Well, if you choose a vertex you can only draw
one diagonal. This one diagonal “splits” the quadrilateral into two triangles.
Since the sum of the internal angles of a triangle are 180 degrees, a quadrilateral has 360 degrees (2 x 180 º ).
The sum of all the interior angles equals 360º degrees.
65º
115º65º
115º65º65º
115º115º+360º
90º
90º
90º
?
90º90º90º
?360º
+ 90º
70º
?
70º
110º
70º70º
110º?+
360º110º
65º
115º65º
?
65º65º
115º?+
360º115º
60º81º
104º?+
360º81º60º
104º?
115º
Now you know that… A quadrilateral is a 4-sided polygon. There are many types of quadrilaterals. ▪ Classification depends on how many sets of sides are
parallel, the length of the sides and the measure of the interior angles.
The sum of the interior angles of a quadrilateral is 360º.