Presentation on theme: "An Introduction to Quadrilaterals"— Presentation transcript:
1An Introduction to Quadrilaterals by Carol Edelstein
2Polygon – a closed, straight-sided, plane figure. DefinitionPolygon – a closed, straight-sided, plane figure.
3Angle – two rays that meet at a common end point. DefinitionAngle – two rays that meet at a common end point.
4DefinitionDegree – a unit of measurement of an angle, represented by the symbol º.90º
5DefinitionDiagonal – a line segment joining two non-adjacent vertices of a polygon.
6Quadrilateral – a polygon with 4 angles and 4 straight sides. DefinitionQuadrilateral – a polygon with 4 angles and 4 straight sides.
7Special Quadrilaterals 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.
8Venn Diagram Persective of Quadrilaterals Quadrilaterals – 4 sided polygonParallelograms(opposite sides are parallel and congruent).Trapezoids(one set of parallel sides)RhombusRectangleSquare
9Quadrilateral Family trapezoid parallelogram rectangle rhombus square
10Property of Quadrilaterals The sum of all the interior angles equals 360º.
11Property of Quadrilaterals 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 ).
12Property of Quadrilaterals The sum of all the interior angles equals 360º degrees.65º65º115º65º115º115º+65º115º360º
13What is the missing angle? 90º90º90º90º90º+90º?90º?360º
14What is the missing angle? 70º70º70º70º110º?110º110º?+360º
15What is the missing angle? 65º65º?65º115º65º115º115º+?360º
16What is the missing angle? 60º81º104º?104º115º60º81º+?360º
17Congratulations and good job! 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.