00:01
We want to find the missing parts of the triangle in degrees rounded to the nearest tenth.
00:07
So if we know that side a is 10, side b is 6, and side c is 9, we want to find angle a, b, and c, we can do this with the law of cosines to start to find angle a.
00:22
The law of cosines would say that side a squared is equal to the sum of the squares of the other two sides, b and c, minus two times.
00:32
Times the product of the other two sides, times the cosine of the included angle a.
00:38
And so we would, to solve for a, subtract six squared, subtract nine squared, and then divide by negative two times six times nine.
00:48
And then that would be equal to the cosine of a.
00:53
So angle a would be the inverse cosine of this ratio.
00:58
So carefully in a calculator, in degree mode, you can find the inverse cosine of 10 squared minus 6 squared minus 9 squared over negative 2 times 6 times 9.
01:24
9...