00:01
Okay, so a walking trail is laid out in the shape of a triangle.
00:03
The lengths of the three paths that make up the trail are 2 ,500 meters, 2 ,000 meters, and 1 ,800 meters, which are meant to be the nearest degree to measure the greatest angle of the trail.
00:14
So because we have three known sides, so first of all, the greatest angle of the trail is going to be the one that's across the 2 ,500.
00:20
So i'm going to find this angle a here.
00:22
And when i do that, i'm going to use the law of cosines, which i wrote out right here.
00:27
I personally like to change this formula to have something that's in reference to cosine or sorry i should i should say that references inverse cosine of a instead of trying to plug all my numbers in now and working through algebraically so for example if i subtract b squared and c squared over to the other side here that's going to turn to a squared minus b b squared minus c squared, and that will be equal to negative 2bc cosine of a.
00:56
Then we can divide both sides by negative 2bc.
01:00
Okay, so once i do that, i'm going to have a squared minus b squared minus c squared over negative 2bc, and that equals the cosine of a...