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Published byLauren Benson Modified over 6 years ago

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DEFINITION: closed plane figure formed by 3 or more line segments such that each segment intersects exactly 2 other segments only at endpoints These figures are not polygonsThese figures are polygons

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DEFINITION: each endpoint of a side of a polygon ◦ Plural is vertices

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Convex: A polygon such that no line containing a side of the polygon contains a point in the interior of the polygon Non-Convex (concave)- a polygon that is not convex

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Equilateral- polygon with all of its sides congruent Equiangular- polygon with all of its interior angles congruent Just like we learned with triangles… but now applies to all polygons!

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Regular- polygon that has all sides and angles congruent Irregular- two sides or interior angles are not congruent

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Diagonal-segment that joins two nonconsecutive vertices of a polygon

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8 Polygon Names 3 sides Triangle 4 sides 5 sides 6 sides 7 sides 8 sides Nonagon Octagon Heptagon Hexagon Pentagon Quadrilateral 10 sides 9 sides 12 sides Decagon Dodecagon n sides n-gon

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The sum of all the exterior angles in a figure is 360. So to find the measure of EACH exterior angle, you divide 360 by the number of sides. On your chart for n-gon please write under the measure of exterior angle of regular polygon. Then fill in the rest of the columns.

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Each exterior and interior angle form supplementary angles. So take 180 – exterior angle to get each interior angle.

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Complete page 2 of your notes by yourself. Then check your answers with the person sitting next to you.

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We can divide a polygon into triangles by drawing the diagonals from 1 vertex. Ex. Draw the diagonals from vertex A of pentagon ABCDE. You should have formed 3 triangles. Draw the diagonals from vertex T in the hexagon PQRSTU. You should have formed 4 triangles. Compare the # of sides in the polygon with the # of s formed. There are 2 fewer s than sides!!

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Therefore, the sum of all of the (interior) angles of a n-gon is (n - 2)180 So fill in these blanks…. The sum of the angles of a pentagon is _______ 180 = __________ The sum of the angles of a hexagon is ________ 180 = __________

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Continue working through your note sheet. If you have questions raise your hand.

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