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6-1 Polygons. Goal 1 Describing Polygons. A polygon is an enclosed plane figure that is made up of segments. Polygons. 3 sided Triangle 4 sided Quadrilateral 5 sided Pentagon 6 sided Hexagon 7 sided Heptagon 8 sided Octagon 9 sided Nonagon 10 sided Decagon
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6-1 Polygons • Goal 1 Describing Polygons
A polygon is an enclosed plane figure that is made up of segments.
Polygons • 3 sided Triangle • 4 sided Quadrilateral • 5 sided Pentagon • 6 sided Hexagon • 7 sided Heptagon • 8 sided Octagon • 9 sided Nonagon • 10 sided Decagon • 11 sided hendecagon • 12 sided Dodecagon
FYI • Names of Polygons • 13 triskaidecagon 14 tetrakaidecagon, tetradecagon 15 pentakaidecagon, pentadecagon 16 hexakaidecagon, hexadecagon 17 heptakaidecagon 18 octakaidecagon 19 enneakaidecagon • 20 icosagon 21 icosikaihenagon, icosihenagon 22 icosikaidigon 23 icosikaitrigon 24 icosikaitetragon 25 icosikaipentagon 26 icosikaihexagon 27 icosikaiheptagon 28 icosikaioctagon 29 icosikaienneagon • 30 triacontagon 31 triacontakaihenagon 32 triacontakaidigon 33 triacontakaitrigon 34 triacontakaitetragon 35 triacontakaipentagon 36 triacontakaihexagon 37 triacontakaiheptagon 38 triacontakaioctagon 39 triacontakaienneagon • 40 tetracontagon 41 tetracontakaihenagon 42 tetracontakaidigon 43 tetracontakaitrigon 44 tetracontakaitetragon 45 tetracontakaipentagon 46 tetracontakaihexagon 47 tetracontakaiheptagon 48 tetracontakaioctagon 49 tetracontakaienneagon • 50 pentacontagon ... 60 hexacontagon ... 70 heptacontagon ... 80 octacontagon ... 90 enneacontagon ...
Polygons Quadrilateral Kite Parallelogram Trapezoid Isosceles trapezoid Rhombus Rectangle Square
Formulas • The sum of the interiors angle of a convex polygon is (n-2)180. • The measure of each interior angle of a regular n-gon is (n-2)180/n • The sum of the measures of the exterior angles of a convex polygon, one angle at each vertgex is 360. • The measure of each exterior angle of a regular n-gon is 360/n.
Parallelogram • A parallelogram is a four-sided figure with both pairs of opposite sides parallel.
Quadrilaterals • Quadrilaterals are four-sided polygons. • <A + <B + <C + <D = 360° A B D C
Properties of a Parallelogram • Both pairs of opposite sides are parallel. • Both pairs of opposite sides are congruent. • Both pairs of opposite angles are congruent. • The diagonals bisect each other. • Consecutive angles are supplementary.
Diagonal • The diagonals of a polygon are the segments that connect any two nonconsecutive vertices.
D C A B • 1. AB // DC, AD // BC • 2. AB =DC, AD = BC • 3. <A = <C and <B = <D • 4. AM = MC and MD = MB • 5. <A + <B = 180 and <B + <C = 180 • <C + <D = 180 and <D + <A = 180
WXYZ is a parallelogram, m<ZWX = b, and m<WXY = d. Find the values of a, b, c, and d. 2c W X 15 a 18° 31° Y Z 22
Ch = • GF // • <DCG = • DC = • <DCG is supplementary to __ • ∆HGC = C G H D F
In parallelogram ABCD, AB = 2x +5, m<BAC = 2y, m<B = 120, m<CAD = 21, and CD= 21. Find the values of x and y.
Quadrilateral WXYZ is a parallelogram with m<W = 47. Find the measure of angles X, Y, and Z.
Assignment • Class work on page 407 • problems 9-20 • Homework page 409, problems 31-36
6-3 Tests for Parallelogram • A Quadrilateral is a parallelogram if any 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.
Polygons Quadrilateral Kite Parallelogram Trapezoid Isosceles trapezoid Rhombus Rectangle Square
Rectangle • A rectangle is a quadrilateral with four right angles.
Properties of a Rectangle • Both pairs of opposite sides are parallel. • Both pairs of opposite sides are congruent. • Both pairs of opposite angles are congruent. • The diagonals bisect each other. • Consecutive angles are supplementary • All angles are congruent • The diagonals are congruent
1. Explain why a rectangle is a special type of parallelogram. • All rectangles are parallelograms, but not all parallelograms are rectangles.
Ex. 2 A rectangular park has two walking paths as shown. If PS = 180 meters and PR = 200 meters, find QT. Q P • 1A If TS = 120m, find PR • If m<PRS =64, find m<SQR S R
Ex. 3 Quadrilateral MNOP is a rectangle. Find the value of x. • MO = 2x – 8; NP = 23 • MO = 4x – 13; PC = x + 7 N M O P
Ex. 4 Use rectangle KLMN and the given information to solve each problem. • M<1 = 70. Find m<2, M<5, M<6 K L 8 1 7 2 C 9 10 6 3 4 5 N M
Ex. 5 Quadrilateral JKLM is a rectangle. If m<KJL = 2x +4 and m<JLK = 7x + 5, find x. J K P L M
6-4 Rhombus • A rhombus is a quadrilateral with four congruent sides.
Assignments6-4 Rectangles • Class work on page 426, problems 10-19 • Homework – problems 26-31
Properties of a Rhombus • Both pairs of opposite sides are parallel. • Both pairs of opposite sides are congruent. • Both pairs of opposite angles are congruent. • The diagonals bisect each other. • Consecutive angles are supplementary • All sides are congruent • The diagonals are perpendicular • The diagonals bisect the opposite angles
Rhombus A B D C
Use rhombus BCDE and the given information to find each missing value. C • If m<1 = 2x + 20 and m<2 = 5x – 4, • find the value of x. • If BD = 15, find BF. • If m<3 = y2 + 26, find y. 1 2 3 B D F E
Square • A square is a quadrilateral with four right angles and four congruent sides.
Properties of a Square • Both pairs of opposite sides are parallel. • Both pairs of opposite sides are congruent. • Both pairs of opposite angles are congruent. • The diagonals bisect each other. • Consecutive angles are supplementary • All angles are congruent. • The diagonals are congruent. • All sides are congruent • The diagonals are perpendicular. • The diagonals bisect the opposite angles.
Assignment 6-5 • Page 435 • Class work – problems 7-12 • Homework – 23-33
Polygons Quadrilateral Kite Parallelogram Trapezoid Isosceles trapezoid Rhombus Rectangle Square
6-6Trapezoids and Kites • A trapezoid is a quadrilateral with exactly one pair of parallel sides. Property • The angles along the legs are supplementary.
base leg leg base
AB // DC • M<A + m<D = 180 • M<B + m<C = 180 A B D C
Isosceles Trapezoid Properties • The legs are congruent • Both pairs of base angles are congruent • The diagonals are congruent
PQRS is an isosceles trapezoid. Find m<P, m<Q, and m<R. P Q 50° S R
Midsegment of a Trapezoid • The midsegment of a trapezoid is parallel to the bases, and its measure is one-half the sum of the measures of the bases.
XY = ½(AB + DC) B A X Y D C
Find the length of the midsegment • When the bases are • 7 and 11 • 3 and 7 • 12 and 7 • 14 and 16 x
Find x 4 7 x
Find x 15 17 x
Find x • AB = ½(EZ + IO) 4x - 10 E Z 13 A B I O 3x + 8
Find x • AB = ½(EZ + IO) 3x-1 E Z 10 A B I O 7x+1
6-6 Assignments • Class work on page 444 • problems 1-11, 16-27