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6.1 Polygons. Week 1 Day 2 January 7 th 2014. State whether the figure is a polygon. If it is not, explain why . Warm UP: Identifying Polygons. Essential Question :. What is a polygon? How do we identify and classify polygons? How do we find angle measures of quadrilaterals? .
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6.1 Polygons Week 1 Day 2 January 7th 2014
State whether the figure is a polygon. If it is not, explain why. Warm UP: Identifying Polygons
Essential Question : • What is a polygon? How do we identify and classify polygons? How do we find angle measures of quadrilaterals?
Vocabulary • Polygon • Sides • Vertex of a polygon • Consecutive vertices • Diagonal of a polygon
Definitions • A polygon is a plane figure that is formed by three or more segments called sides. (a closed, sided figure) • Each side intersects exactly two other sides at each of its endpoints. Each endpoint is a vertex of the polygon. • Two vertices that are endpoints of the same side are consecutive vertices. • A segment that joins two nonconsecutive vertices of a polygon is called a diagonal. side Vertices diagonal Consecutive vertices
State whether the figure is a polygon. If it is not, explain why. Not D – has a side that isn’t a segment – it’s an arc. Not E– because two of the sides intersect only one other side. Not F because some of its sides intersect more than two sides. Warm UP: Identifying Polygons Figures A, B, and C are polygons.
Polygons are named by the number of sides they have. Fill in the blank. Quadrilateral Pentagon Hexagon Heptagon Octagon
Quadrilateral Interior Angles Theorem • The sum of the measures of the interior angles of a quadrilateral is 360°. B m<A + m<B + m<C + m<D = 360° C A D
Example • Find m<Q and m<R. x + 2x + 70° + 80° = 360° 3x + 150 ° = 360 ° 3x = 210 ° x = 70 ° Q x 2x° R 80° P 70° m< Q = x m< Q = 70 ° m<R = 2x m<R = 2(70°) m<R = 140 ° S
Homework • Page 306 # 8-10, 16, 18