Question

1.) The area of a regular octagon is 35 cm squared. What is the area of a regular octagon with sides three times as long?

My answer: 315 cm squared. Is that correct?

2.) Name the minor arc and find its measure.

http://assets.openstudy.com/updates/attachments/4fb5f543e4b05565342bcb5a-kamuela710-1337324879047-4568453162011122648pm17916

My answer: ADB has a measure of 245. Is that correct?

Answer 1

3.) The figures below are similar. What are a) the ratio of the perimeters and b) the ratio of the areas of the larger figure to the smaller figure? The figures are not drawn to scale.

http://assets.openstudy.com/updates/attachments/55bcef17e4b0c4d93d6c2874-lollygirl217-1438476949164-as.jpg

My answer: 13/3=169/9. Is that correct?

Answer 2

@Michele_Laino @triciaal

Answer 3

@pooja195 @ganeshie8

Answer 4

@amistre64

Answer 5

@nincompoop

Answer 6

@undeadknight26

Answer 7

how do we determine the area of a regular octagon to start with?

Answer 8

im pretty sure the general solution is that a change in linear measures, scale by ^2 in area

Answer 9

so 315 sounds good to me, but i always have to dbl chk with the brute method since i cant recall thrms that well

Answer 10

Alright, do your thing.

Answer 11

a triangle ... base s, apothem a, area = sa/2 and there is 8 of them

area = 4 sa

linear measures factor by 3 so: 4(3s)(3a) = 3^2 (4sa)

in this case 3^2 (35) is good

Answer 12

the link to the arc is bad

Answer 13

Oh it is? Hold on.

Answer 14

ok, and what does it mean to be a minor arc?

Answer 15

@amistre64 well firsts things first. Did I get any of them right?

Answer 16

I mean that one right.

Answer 17

yes, i verified that 315 is correct.

on the second one, and the third one, i would perfer to see how you came to your solutions first tho.

Answer 18

to determine the solution to number 2, we need to agree on the definition of a minor arc.

Answer 19

Perhaps it's just AB has a measure of 245.

Answer 20

AB is minor because of the two arcs in the circle AB has a measure of 115 degrees and ADB has a measure of 245. This is what I say

Answer 21

perhaps, but that depends on what our definition of a minor arc is ...

Answer 22

AB is minor, agreed, since it is less then 180 .. and it is measured for us already as 115

Answer 23

we good to move on to #3?

Answer 24

So then it would be ab measured as 115?

Answer 25

correct

Answer 26

Lol...how did I make that mistake?

Answer 27

:) pretty sure you read minor as "major" ... i read things too fast sometimes as well

Answer 28

Yeah, I did.

Answer 29

tell me how you approached #3

Answer 30

a) ratio of perimeters = 26/6 = 13/3
b) ratio of areas = (13/3)² = 169/9 <----------A = L²

Answer 31

i like it.

Answer 32

not sure if the notation is correct, since im not taking your class specifically

13:3, or 1 : 13/3 is what i am used to playing with

Answer 33

if the ratio of sides of similar shapes is: 1:k

the ratio of their ares is: 1:k^2

Answer 34

So it is 13/3, I got have of it right. Then it must be 13/3 and 16/9

Answer 35

Or are you saying I got it right??

Answer 36

you got it right; 13/3 and 13^2/3^2 is fine

Answer 37

13^2 = 169
3^2 = 9

just make sure your notation is accurate to your course.

Answer 38

going from large to small might mean:

3/13 and 9/169

Answer 39

Alright thank you.