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Chapter 8. Quadrilaterals. What is a quadrilateral?. A polygon that has four sides. Examples. Classification of Quadrilaterals. Two pairs of parallel sides (Parallelogram) One pair of parallel sides (Trapezoid) No sides parallel (Kite). A quadrilateral with 2 pairs of parallel sides.
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Chapter 8 Quadrilaterals
What is a quadrilateral? • A polygon that has four sides. Examples
Classification of Quadrilaterals • Two pairs of parallel sides (Parallelogram) • One pair of parallel sides (Trapezoid) • No sides parallel(Kite)
A quadrilateral with 2 pairs of parallel sides What is a parallelogram Example A B C D
What is a rectangle? • A Quadrilateral with 4 right angles Example A B C D
What is a rhombus A Quadrilateral with 4 congruent sides A D B C
What is a Square A quadrilateral with 4 right angles and 4 congruent sides Example A B D C
Types of parallelograms • Rectangles • Rhombus • Square
Both pairs of opposite sides parallel Opposite sides congruent Opposite angles congruent Consecutive angles supplementary AB || DC & AD || BC AB = DC & AD = BC <A = <C & <B = <D <A + <B = 180 <B + <C = 180 <C + <D = 180 <D + <A = 180 Properties of a parallelogram
5. Diagonals bisect each other AE = EC & DE = EB Properties of parallelogram cont.
5 properties of a ||ogram + 6. 4 right angles 7. Diagonals are congruent <A, <B, <C, & <D are right angles AC = DB Properties of a rectangle
5 properties of a ||ogram + 6. 4 sides are congruent 7. Diagonals are perpendicular 8. Diagonals bisect opposite angles AB = BC = CD = DA <AEB is a right angle <ABE = <EBC Properties of a rhombus
Properties of a square • All properties of a ||ogram • All properties of a rectangle • All properties of a rhombus
A Quadrilateral is a parallelogram if any one of the following is true. • Both pairs of opposite sides are parallel. • Both pairs of opposite sides are congruent. • Both pairs of opposite angles are congruent. • Diagonals bisect each other. • A pair of opposite sides is both parallel and congruent.
Trapezoid • A quadrilateral with one pair of sides parallel
Bases Legs Base angles Sides that are parallel Nonparallel sides (congruent sides) A pair of angles on the same side with a base Parts of a trapezoid base leg leg Base angle base Base angle
Special Trapezoid • Isosceles Trapezoid – trapezoid that has congruent legs
Properties of Isosceles Trapezoid • Legs are congruent • Both pairs of base angles are congruent • The diagonals are congruent
What is a median ? • Segment that joins the midpoints of the legs • Parallel to the bases
Finding the median • Median = ½ (base1 + base2)
Example • Given trapezoid GHIJ with median KL, find the value of x. KL = ½ (GH + JI) 10 = ½ ( 3x – 1 + 7x +1) 10 = ½ ( 10x ) 10 = 5x 2 = x G 3x – 1 H 10 L K J 7x + 1 I
Example 2 • Given trapezoid WXYZ with median MN, find XY, if MN = 10 and WZ = 14. MN = ½(XY + WZ) 10 = ½ (XY + 14) 20 = XY + 14 6 = XY Z W N M X Y