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Mathematics 8 Online
OpenStudy (anonymous):

REALLY REALLY NEED HELP WITH THIS A carnival ride is in the shape of a wheel with a radius of 25 feet. The wheel has 20 cars attached to the center of the wheel. What is the central angle, arc length, and area of a sector between any two cars? Round answers to the nearest hundredth if applicable. You must show all work and calculations to receive credit.

OpenStudy (anonymous):

PLEASE HELP

jimthompson5910 (jim_thompson5910):

let's say there are 2 cars equally spaced apart (and only two cars) what's the central angle?

OpenStudy (anonymous):

180? @jim_thompson5910

jimthompson5910 (jim_thompson5910):

how did you calculate that

OpenStudy (anonymous):

because there are 2 cars and the degrees of circle is 360 so 360/2 is 180

jimthompson5910 (jim_thompson5910):

good, so with 20 cars, you'd have 360/20 = 18 degrees as the central angle (between two adjacent cars)

jimthompson5910 (jim_thompson5910):

what's the circumference of this whole circle?

OpenStudy (anonymous):

okay I got that part

OpenStudy (anonymous):

idk the circumference idk how to get that :(

jimthompson5910 (jim_thompson5910):

use the formula C = 2*pi*r

OpenStudy (anonymous):

okay so 157

jimthompson5910 (jim_thompson5910):

I'd leave it in terms of pi

jimthompson5910 (jim_thompson5910):

actually they want you to "Round answers to the nearest hundredth if applicable"

jimthompson5910 (jim_thompson5910):

but that's not the answer, so leave it in terms of pi for now C = 2*pi*r C = 2*pi*25 C = 50pi That's the exact circumference

OpenStudy (anonymous):

whats terms of pi? I thought the answer was 157

jimthompson5910 (jim_thompson5910):

the arc length between two adjacent cars is going to be 18/360 = 1/20 of the whole circumference (ie we're cutting up the perimeter of the circle into twenty equal pieces)

jimthompson5910 (jim_thompson5910):

so (1/20)*50pi = (50/20)*pi = (5/2)*pi is the exact arc length between two adjacent cars

OpenStudy (anonymous):

but why don't we just use 3.14 for pi since it says round? its not asking for an exact answer

jimthompson5910 (jim_thompson5910):

alright, go ahead and use the approximation pi = 3.14

OpenStudy (anonymous):

so would the arc length be 7.85

OpenStudy (anonymous):

157/20 ?

jimthompson5910 (jim_thompson5910):

157 is close, but not quite the circumference

jimthompson5910 (jim_thompson5910):

so I wouldn't use 157

jimthompson5910 (jim_thompson5910):

7.85 is what I'm getting for the arc length

jimthompson5910 (jim_thompson5910):

What is the area of the circle?

OpenStudy (anonymous):

idk the area I have no clue how to get it

jimthompson5910 (jim_thompson5910):

use A = pi*r^2

OpenStudy (anonymous):

1962.5?

jimthompson5910 (jim_thompson5910):

roughly, yes

jimthompson5910 (jim_thompson5910):

now divide that by 20 to split the whole circle into 20 equal pieces (or slices)

jimthompson5910 (jim_thompson5910):

this will give you the rough area of the sector

jimthompson5910 (jim_thompson5910):

so again, the arc length is found by dividing the circumference by 20 the area of the sector is found by dividing the area by 20

OpenStudy (anonymous):

okay cool thanks

OpenStudy (anonymous):

and whats the central angle?

jimthompson5910 (jim_thompson5910):

it's shown above when we divided the 360 degrees into 20 equal pieces

OpenStudy (anonymous):

oh okay thank you

jimthompson5910 (jim_thompson5910):

np

OpenStudy (anonymous):

i have a few more questions, can i tag you in them for help?

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