00:01
Problem, we're given a cord of 26 centimeters and a radius of 20 centimeters.
00:04
We want to find the length of the arc, which is denoted as x here.
00:09
So we know that arc length follows the formula r theta.
00:14
We have r, that's 20, but we don't have theta.
00:18
We need to find this angle in radiance.
00:21
So we're going to do this using the cosine law.
00:26
Cosine law says c squared equals a squared, let's b squared minus 2 a b, cosine, uh, theta, or cosine angle c.
00:36
So this is 26 squared equals 20 squared plus 20 squared minus 2 times 20 times 20, and uh, 26 squared minus 20 squared minus 20 squared...