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Sec 1-6 Concept: Polygons Objective: Given a figure, we will identify and name it if it is a polygon as measured by a scoring guide Vocabulary: Polygon: a plane figure that meets these 2 criteria 1. It is formed by three or more line segments called sides 2. each side intersects exactly two sides, one at each endpoint, so that no two sides with a common endpoint are collinear. Vertex N O S W Polygon SNOW Example 1: Determine which shapes are polygons. If a shape is a polygon, then state if it is concave or convex. A B C A - yes D concave B - no C - yes concave D - yes convex Names of Polygons: Handout You have 10 min. to do this handout, then we will go over it Regular Polygon: A regular polygon is both equilateral and equiangular Example 2: Each figure is a regular polygon. Expressions are given for two sides lengths. Find the value of x. x2+5x+13 7x+34 11x-14 x2+10x-7 7x+34 = 11x-14 x2+5x+13 = x2+10x-7 48=4x 20=5x 12=x 4=x Example 3: The expressions (3x+63)° and (7x-45)° represent the measures of two angles of a regular decagon. Find the measure of an angle of the decagon. 3x+63=7x-45 3(27)+63 108=4x =144° 27=x Example 4: Draw a figure that fits the description. 1. A quadrilateral that is not regular 2. A concave pentagon Example 5 # 31 p. 46 Example 6 # 33 & 36 p. 46 Today’s Work: