Warm-Up – 10/27/09 #6
Do you know where your warm up sheet is?
Draw the following triangles using correct notation: A) obtuse isosceles B) acute scalene C) right isosceles
Homework Answers 5. 6. 7. 8. 9. 10.
180 30 95 50 25 360
11. 12. 13. 14.
x=30, y=80 x=110, y=70 x=40, y=50 x=90, y=25
3.5 Angles of a Polygon Objective – Find measures of interior and exterior angles of a polygon.
Polygon ď Ž
Many Sided figure
Convex Polygon Convex
Nonconvex “Concave”
Naming a Polygon ď Ž
List the consecutive vertices in order B C A
D E
Diagonal ď Ž
Segment joining two nonconsecutive D vertices E C
B
A
Polygon Classification by Sides
Number 3 4 5 6 7 8 9 10 n
Name
Triangle Quadrilateral Pentagon Hexagon Heptagon Octagon Nonagon Decagon N-gon
Interior Angle Sum
Sum of interior angles of polygon: (n – 2) ∙180 n = number of sides
Exterior Angle Sum ď Ž
The sum of exterior angles of polygon:
360
Regular Polygons ď Ž
Both equilateral and equiangular
ď Ž
Can you think of a regular polygon?
Example 1 ď Ž
A regular polygon has 12 sides. Find the measure of each interior angle and each exterior angle.
Example 2 ď Ž
Find the number of sides of a regular polygon if each interior angle is 140.
Example 3 ď Ž
Find n if the measure of each exterior angle is 24.
Homework…
Page 104; 1-15 no #7