00:01
We're going to calculate the arc length of a circle today, and we're going to do that using a proportion.
00:07
So we know that our radius is equal to five centimeters, and we know that our arc has a measure, or i'm sorry, our central angle, has a measure of 45 degrees.
00:23
So first we need to find the circumference of our circle using the formula 2 pi r.
00:30
In our case, r is 5, so 2 times 5 would be equal to 10 pi.
00:37
And if i have 10 times pi and i use 3 .14 for pi, i will get 31 .4 centimeters for my total circumference.
00:49
So now we can set up our proportion using a part over a whole.
00:54
And when i do that, i'll have 45 degrees over 360 degrees, our part over our whole, is equal to x, that's our arc length that we don't know, over the whole...