Here's the question you clicked on:
stupidinmath
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you have two arcs of radius 10
each arc is measuring exactly 1/4th of circle (why ?)
so you can calculate the perimeter of shaded region ?
so.. if i get the arc measures.. i'll just add both then i can already have the perimeter?
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)
my answer is.. P=900, is it correct?
Seems wrong. \[\pi \] Is missing for sure.
What is the perimeter of a circle with radius=r?
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?
yep, perimeter's 62.83 approximately
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?
Correct, thus one arc has perimeter: \[\frac{ 1 }{ 4 } 2\pi r \]
We need two arcs, so need to multiply the above equation by 2. \[2*\frac{ 1 }{ 4 } 2\pi r =\pi r\]
15.71.. so.. 31.42 :)
did i get it right?
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 \[10 \pi \]
Hahah, yeah maybe. Alright. Got that. Thank you sooo much:)
@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.
You might be right but that hurts my soul :(