00:01
Okay, so we want to find the exact value of sine of negative 5 pi over 12.
00:06
So let's note that we can read this as sign of, that's going to be pi over 3 minus 3 pi over 4.
00:15
And now let's use our formula for sine of x minus y.
00:20
So that's going to be sine of pi over 3 and then cosine of 3 pi over 4.
00:28
And then we have, let's see, sign that's going to be minus, cosine of pi over 3, and then sign of 3 pi over 4.
00:41
Okay, so let's recall our right triangle for pi over 3, that's the square root of 3, 1, and 2, and for cosine, or for 3 pi over 4, we know that this is in quadrant 2.
01:01
So our x term is negative...