Help?
For this circle, a 70 degree central angle cut off an arc of 8 in. What is the circumference of the circle?

Question

Help?
For this circle, a 70 degree central angle cut off an arc of 8 in. What is the circumference of the circle?

anonymous · Answer

$$\theta = arc/radius$$

anonymous · Answer

Hint: angle must be in Radian

anonymous · Answer

After finding the radius

Circum..... = 2 pie r

anonymous · Answer

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anonymous · Answer

@Yahoo!  What's radian?

anonymous · Answer

it is a kind of way to measure angle

anonymous · Answer

pie radian = 180 degree

anonymous · Answer

For the radian I got 1.2 rad.

anonymous · Answer

Then it's something like 1.2rad=8/r?

directrix · Answer

Think of 360 degrees as being analogous to 2*pi*r as the circumference of the circle.

So,  70/360 = 8/(2 * pi* r) where r is the radius of the circle.

directrix · Answer

r = 144/(7*pi)

To find the circumference, C = 2 * pi* r.

Substitute for r and solve.

C = 2 * pi* [ (144/(7*pi))]

anonymous · Answer

I got 41.1

directrix · Answer

41.143 inches approx is what I got. So, we agree.

anonymous · Answer

The choose was rounded. But thank you so much. I can't believe that is 6th grade math...

directrix · Answer

Sixth grade math varies. I don't know the context of the problem or how the sixth graders were taught to think about this problem.

anonymous · Answer

My sister said they've never seen this before in her entire year and I'm a sophomore and I've never seen it either. Being in Algebra II I thought I had seen it before. I guess everywhere is different though.

directrix · Answer

The algebraic approach - writing and solving an equation - usually comes in a Geometry class. At least, that is where I have seen  it.