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Section 5.4 Four-Sided Polygons By: Laura Moeller Kristie Furiosi. WHAT IS A POLYGON?. A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others. The following are examples of polygons:. WHAT IS NOT A POLYGON?.
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Section 5.4 Four-Sided Polygons By: Laura Moeller Kristie Furiosi
WHAT IS A POLYGON? • A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others. • The following are examples of polygons:
WHAT IS NOT A POLYGON? • The figure below is not a polygon since it is not a closed figure: • The figure below is not a polygon since it is not made of line segments:
Naming Polygons • Polygons are named starting at one vertex, then continuing clockwise or counter-clockwise. • This polygon can be named LKBFJM, or LMJFBK starting at point L. (Polygon Laura Kristie Beatrice Furiosi Jane Moeller) L K B F J M
Diagonals of Polygons • Diagonals are the segments that connect two nonconsecutive vertices of the polygon. • LV and EO are diagonals of rectangle LOVE. L O E V
QUADTILATERALS QUADRILATERALS: four-sided polygons The following are examples of quadrilaterals:
TYPES OF QUADRILATERALS • PARALLELOGRAM- a quadrilateral in which both pairs of opposite sides are parallel or congruent. K F K F L M L M
TYPES OF QUADRILATERALS • RECTANGLE- a parallelogram in which at least one angle is a right angle Figure HANK is a parallelogram H A K N <N is a right angle, therefore, HANK is a rectangle
TYPES OF QUADRILATERALS • RHOMBUS- A parallelogram in which at least two consecutive sides are congruent.
TYPES OF QUADRILATERALS • KITE- a quadrilateral in which two disjoint pairs of consecutive sides are congruent.
TYPES OF QUADRILATERALS • SQUARES- a parallelogram that is both a rectangle and a rhombus.
TYPES OF QUADRILATERALS • TRAPEZOID- a quadrilateral with exactly one pair of parallel sides. The parallel sides are called the bases of the trapezoid. B A D C
TYPES OF QUADRILATERALS • ISOSCELES TRAPEZOID- a trapezoid in which the nonparallel sides (legs) are congruent.
Sample Problem 1 K Given: KFLM is a kite. KF = x + 7 FL = x + 8 LM = 3x – 7 MK = 4x – y • Solve for x and y. • What is the perimeter of the kite? M F L
Answer to Sample Problem 1 x + 8 = 3x – 7 4x – y = x + 7 -2x = -7 – 8 4(7.5) – y = 7.5 + 7 -2x = -15 30 – y = 14.5 x = 7.5 -y = 14.5 – 30 -y = -15.5 y=15.5 • x = 7.5, y = 15.5 • Perimeter of KFLM = 60
Sample Problem 2 Find the area of a square if the perimeter is 70. A B D C
Answer to Sample Problem 2 70 4 = 17.5 17.5 x 17.5 = 306.25 The area of square ABCD is 306.25 A B C D
Practice Problems True of False? A rectangle has four congruent sides… A parallelogram has one pair of opposite sides parallel… The non-parallel sides of a trapezoid are the bases… A quadrilateral has four sides… A rectangle has at least one right angle…
Answers to Practice Problems True or False? False- only the opposite sides of a rectangle are congruent. False- A parallelogram has two pairs of opposite sides parallel. False- The non-parallel sides of a trapezoid are the legs. True True
More Practice Problems Examine the statements below. If the statement is always true, write A; if sometimes true, write S; if never true, write N. • A rectangle is a polygon. • A trapezoid has 3 bases. • A kite is a parallelogram. • A square is a rhombus.
Answers to Practice Problems • Always • Never – a trapezoid only has 2 bases • Sometimes – a rhombus is not only a kite, but a parallelogram • Always
WARNING RANDOM POLYGON VIDEOmay cause extreme headaches and annoyance
Works Cited "2D Geometric shapes." Math Worksheets, Tables, Charts and more from HelpingWithMath.com. Web. 17 Jan. 2010. <http://www.helpingwithmath.com/by_subject/geometry/geo_shapes.htm>. "Figures and Polygons." Web. 17 Jan. 2010. <http://www.mathleague.com/help/geometry/polygons.htm>. Milauskas, George, and Robert Whipple. Geometry for Enjoyment & Challenge. Boston: Houghton Mifflin Company, 1991. Print. "Quadrilaterals - Square, Rectangle, Rhombus, Trapezoid, Parallelogram." Math is Fun - Maths Resources. Web. 17 Jan. 2010. <http://www.mathsisfun.com/quadrilaterals.html>.