8.2 Polygons 471 Exercises Warm Up Exercises In Exercises 1– 6, fill in the blanks with an appropriate word, phrase, or symbol(s). 1. A closed figure in a plane determined by three or more straight line segments is called a(n) ________. Polygon 2. A polygon whose sides are all the same length and whose interior angles all have the same measure is called a(n) ________ polygon. Regular 3. Two polygons are similar if their corresponding angles have the same measure and the lengths of their corresponding sides are in ________. Proportion 4. The sum of the measures of the interior angles of a triangle is ________. ° 180 5. If the corresponding sides of two similar figures are the same length, the figures are called ________ figures. Congruent 6. The sum of the measures of the interior angles of a quadrilateral is ________. ° 360 Practice the Skills In Exercises 7–14, (a) name the polygon. (b) State whether or not the polygon is a regular polygon. 7. a) Pentagon b) Regular 8. a) Hexagon b) Regular 9. a) Heptagon b) Regular 10. a) Dodecagon b) Regular 11. a) Heptagon b) Not regular 12. a) Octagon b) Regular 13. a) Decagon b) Regular 14. a) Dodecagon b) Not regular In Exercises 15–22, identify the triangle as (a) scalene, isosceles, or equilateral and as (b) acute, obtuse, or right. The parallel markings (the two small parallel lines) on two or more sides indicate that the marked sides are of equal length. 15. a) Isosceles b) Right 16. a) Scalene b) Right 17. a) Isosceles b) Acute 18. a) Isosceles b) Obtuse 19. a) Scalene b) Acute 20. a) Scalene b) Right 21. a) Equilateral b) Acute 22. a) Scalene b) Obtuse SECTION 8.2
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