00:01
We can use the law of cosines to solve for the side c that is across from the angle c, which has 120 degrees.
00:09
And then we will go from there.
00:11
So let's do that.
00:12
The law of cosine says that c squared is equal to a squared plus b squared minus 2ab times the cosine of the angle c.
00:24
So if we put into our equation the values we know, then we will have 36.
00:30
Because that's 6 squared, 49 because that's 7 squared for a squared and b squared, then minus 2 times 6 times 7 times the cosine of 120 degrees.
00:45
We can evaluate this all at once, and we will get 127.
00:53
So now we just need to take the square root of both sides, and we get the square root of 127, and we get the square root of 127.
01:02
Which is approximately 11 .23.
01:08
Excuse me, 27.
01:12
Okay, and now that we know c is 11 .27, we can use the law of signs to solve for one of the other angles...