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owenflo

Member

Registered: 2014-07-21

Posts: 115

POLYGONS please HELP ME CHECK

Give the number of diagonals for the following polygons:

1. triangle

A0
B1
C2
D3
E 4
F 5

2. quadrilateral

A1
B2
C3
D4
E 5
F 6

3. pentagon

A0
B1
C2
D3
E 4
F 5

4. hexagon

A7
B3
C2
D9
E 12
F 8

5. octagon

A20
B11
C4
D7
E 13
F 5

6. decagon

A22
B5
C35
D8
E 11
F 14

1.A
2.B
3. F
4. D
5.A
6.C

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: POLYGONS please HELP ME CHECK

Hi;

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

owenflo

Member

Registered: 2014-07-21

Posts: 115

Re: POLYGONS please HELP ME CHECK

So all correct?

owenflo

Member

Registered: 2014-07-21

Posts: 115

Re: POLYGONS please HELP ME CHECK

7. duodecagon

A87
B54
C15
D20
E 9
F 34

8. pentadecagon

A90
B44
C10
D61
E 37
F 29

7. D
8.F

owenflo

Member

Registered: 2014-07-21

Posts: 115

Re: POLYGONS please HELP ME CHECK

9. If N = 11

A30
B26
C7
D44
E 11
F 18

10. If N = 43

A452
B554
C624
D860
E 721
F 631

11. If N = 55

A1007
B2214
C1997
D1838
E 1430
F 1112

12. If N = 20

A684
B340
C111
D170
E 573
F 890

13. If N = 89

A1324
B3124
C7519
D 5449
E 3827
F 8791

14. If N = 33

A495
B813
C368
D598
E 245
F 438

In the next 5 questions, we will be using the information we learned from the "paragraph proof" in the lesson to determine the sum of the inner angles of regular polygons.

15. Since a pentagon is a closed shape, what must the sum of the angles of deviation be?

A270o
B180o
C90o
D60o
E 320o
F 360o

16. Divide that number by the number of angles a pentagon has to get the degree measure of a single angle of deviation:

A2o
B359o
C471o
D72o
E 6o
F 7o

17. In the paragraph proof it says: "The inner angles of the triangle are supplementary to the angles of deviation, therefore, the sum of each inner angle and its corresponding angle of deviation is 180." Using the number you got from #16, subtract the angle of deviation from 180o to get the measure of a single inner angle:

A70o
B82o
C142o
D85o
E 108o
F 42o

18. What is the sum of all of the inner angles of a pentagon?

A540o
B432o
C360o
D112o
E 180o
F 900o

19. Using the same or a similar process, what is the measure of a single angle of deviation on a regular octagon?

A72o
B45o
C83o
D40o
E 8o
F 42o

20. Using the same or a similar process, what is the sum of the inner angles of an octagon?

A600o
B180o
C540o
D360o
E 2489o
F 1080o

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: POLYGONS please HELP ME CHECK

Hi;

So all correct?

Here is the formula to figure these out.

http://www.mathsisfun.com/geometry/poly … onals.html

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.