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.