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Polygons. Geometry Unit 2. Polygon:. Origin: Greek “Poly-” meaning “many” and “- gon ” meaning “angle” Definition: a 2-dimensional, closed, shape made of three or more straight lines. NOT A POLYGON!. POLYGON!. POLYGON!. NOT A POLYGON!. POLYGON!. POLYGON!. The BASIC Polygons – Part 1.
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Polygons Geometry Unit 2
Polygon: • Origin: Greek “Poly-” meaning “many” and“-gon” meaning “angle” • Definition: a 2-dimensional, closed, shape made of three or more straight lines.
NOT A POLYGON! POLYGON! POLYGON! NOT A POLYGON! POLYGON! POLYGON!
The BASIC Polygons – Part 1 Triangle Quadrilateral Pentagon Hexagon
The BASIC Polygons – Part 2 Heptagon Octagon Nonagon Decagon
The BASIC Polygons – Part 3 dodecagon n-gon
Sum of the interior • We can find the sum of the interior angles of any polygon using the formula • Sum = 180(n-2) • n = the number of sides Back to the chart
The BASIC Polygons – Part 1 180° Triangle 360° Quadrilateral 540° Pentagon 720° Hexagon
The BASIC Polygons – Part 2 900° Heptagon 1080° Octagon 1260° Nonagon 1440° Decagon
The BASIC Polygons – Part 3 1800° dodecagon 180(n-2)° n-gon
The algebra of Sum of the interior • Find the value of x. • (4x) + 113 + (2x + 9) + (3x + 8) + 113 = 540 113° X = 33
More Interior Angle Stuff • The sum of the interior angles of a polygon is 1620 degrees. What is the name of the polygon? 11-gon We’ll know tomorrow
Sum of the Exterior • The sum of the exterior angles of a polygon is simple … it always equals • 360°
A single exterior angle • Find the measure of an exterior angle of a regular heptagon. Round to the nearest tenth if necessary. 51.4°
Interior and Exterior • What is the relationship between an individual interior and exterior angle? • They are supplementary
More Algebra • Find the value of x. • x + 138 + 2x + 100 + 110 = 540 138° 100° X = 64