Question

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Answer 1

you have two arcs of radius 10

Answer 2

each arc is measuring exactly 1/4th of circle (why ?)

Answer 3

so you can calculate the perimeter of shaded region ?

Answer 4

so.. if i get the arc measures.. i'll just add both then i can already have the perimeter?

Answer 5

Do you know what is the perimeter of a full circle?
If you do you can find the shaded one. As that is twice the quarter of a circle. Thus 2*1/4=1/2
The perimeter is half of the full circle. (with radius=10)

Answer 6

my answer is.. P=900, is it correct?

Answer 7

Seems wrong. \[\pi \]
Is missing for sure.

Answer 8

What is the perimeter of a circle with radius=r?

Answer 9

15.71 ?

Answer 10

62.83

Answer 11

Do not try to jump steps. One at a time, otherwise you will make too many mistakes.
So we will start with a circle of any radius=r.
This circle has perimeter:
\[P=2\pi r \]
Is this clear?

Answer 12

yep, perimeter's 62.83 approximately

Answer 13

If r=10 as in this question.
Now next step, first look at one arc of the graph. (half the perimeter asked)
What fraction is this arc of the full circle?

Answer 14

1/4 of the circle

Answer 15

Correct, thus one arc has perimeter:
\[\frac{ 1 }{ 4 } 2\pi r \]

Answer 16

We need two arcs, so need to multiply the above equation by 2.
\[2*\frac{ 1 }{ 4 } 2\pi r =\pi r\]

Answer 17

\[solution: P=10\pi \]

Answer 18

15.71..
so.. 31.42 :)

Answer 19

did i get it right?

Answer 20

Yes but I am 100% confident that your maths teacher will not like the solution written as 31.42, as it is not precise. The solution is \[10 \pi \]

Answer 21

Hahah, yeah maybe. Alright. Got that.
Thank you sooo much:)

Answer 22

@Andras Don't be so sure. Often times in courses like this the teacher prefers that you assume pi=3.14, which is probably exactly what his teacher expects since he's already doing it this way.

Answer 23

You might be right but that hurts my soul :(