Warm-up after 5.1 Day 1:1. Find the sum of the interior and exterior angles of a pentagon.

sum int. ∠s = ____ sum ext. ∠s = ____

2. The sum of interior angles of a convex polygon is 1080. Classify the polygon by its sides.

3. What is a regular polygon?

______________

Geometry Section 5.1Day 2

Polygons &

their angle measures

Learning Target:I can calculate angle measure for angles of polygons. [G.MG.1]

Review 5.1 Day 1Polygons• What 3 things do you need to check for to be a polygon?

• Can you classify a polygon by its sides?

• Equilateral, Equiangular, Regular

• Convex or concave?

• Sum of the interior angles = _______________________

where n is _________________________

• Sum of the exterior angles = _________

*ex - pentagon

xo

(x + 20)˚

112˚96o

2. Find the value of x.

1. Find the value of x. Hint: find the sum of the interior angles first

Hint: find the sum of the exterior angles first

3. Find the measure of one interior ∠ AND one exterior ∠ on a stop sign.

In a Regular Polygon,

Each Interior =

Each Exterior =

where n is the number of sides

4. If each exterior angle of a regular n-gon is 15˚,

then how many sides does the n-gon have?

5. Each interior angle of the regular n-gon has a measure is 162˚. Find the value of n.

OR

Homework:

Sum Interior = (n – 2) • 180

Sum Exterior = 360˚

In a Regular Polygon

Each Interior =n

(n – 2) •180

Each Exterior = n 360

Assignment: Finish 5.1 worksheet

Geometry 5.1 WS Answers1. 1440˚ 2. 4140˚

3. octagon 4. 20-gon

5. x = 53 6. x = 82

7. x = 117 8. x = 111

9. x = 66 10. x = 150

11. x = 36, largest angle =___ 12. x = ___ , smallest angle = 40

13. 1 int angle = 160˚ , 1 ext angle = 20˚

14. 40 sides 15. 15 sides

MUSTShow work#5-15!