Question

Please help with Study Island? Calculating circles

Answer 1

Can someone explain how to find this please?

Answer 2

@jdoe0001 I was thinking about you on this one lol
I just need to refresh my memory from last time! I remember 120/360 x 2 x Pi x r??

Answer 3

Was that the formula?

Answer 4

hmm Area of a Segment of a Circle = \(\bf \cfrac{\theta \pi r^2}{360}\)

Answer 5

I got 126.65 then

Answer 6

use the angle at the centre to determine the fraction

every circle contains 360 degrees

so the fraction is for the blue sector is 120/360

for the blue area, take the total area you have been given and multiply by the fraction 120/360

Answer 7

http://openstudy.com/study#/updates/529f8cb5e4b0d45cde21806a <--- notice towards the end

Answer 8

Thank you @campbell_st!!
And thanks @jdoe0001 I keep forgetting that formula you're using because in class we're taught it kind of different I think, but I guess it works both ways. So 126.65 would be the right answer?

Answer 9

let's firstly find the radius of it, we know the Circle's Area is 121 so \(\bf Area = \pi r^2\qquad Area = 121\implies \pi r^2=121\implies r=\sqrt{\cfrac{120}{\pi}}\)

Answer 10

The radius = 11

Answer 11

then you use that radius and plug it in \(\bf \bf \cfrac{120 \pi r^2}{360}\)

Answer 12

Ahhh it's so much easier that way! I'm starting to understand it more, thanks again : ) I'll try to remember it

Answer 13

actually... even easier... one sec