00:01
Here we're looking for the circumference of each circle and we're told to use 3 .14 for the value of pi.
00:06
So pi equals 3 .14 and circumference is 2 pi r.
00:16
2 times pi times the radius.
00:18
Okay, so if we look at number 1, the radius is 12 centimeters.
00:24
And i know this because the radius goes from the center of the circle to the edge and it's given to me in this circle.
00:30
So therefore the circumference equals 2 times pi, which we said is 3 .14, times the radius, which is 12.
00:40
So i get circumference, and you can put this in your calculator just like this.
00:44
2 times 3 .14 times 12.
00:48
And we find that the circumference is 75 .36 centimeters.
00:54
Number 2, we're given a radius of 10 centimeters and our circumference is 2 pi r.
01:07
So we get 2 times 3 .14 times 10.
01:15
2 times 3 .14 times 10 gives me a circumference of 62 .8 centimeters.
01:25
3, i'm given a radius of 0 .6 inches.
01:32
Circumference equals 2 pi r.
01:36
So my circumference is 2 times 3 .14 times 0 .6...