00:01
We are going to find the definite integral of sine of x plus cosine of x from negative pi over 4 to 7 pi or 4.
00:07
To do this, we will use the fundamental theorem of calculus, which says that we are going to find the antideributive of sine of x plus cosine x and then evaluate those at the bounds.
00:17
So the anti -derivative of sine of x is going to be in this case negative cosine of x, and the antiderivative of cosine of x is sine of x.
00:27
And we are going to again evaluate those at the bounds that we are given on our integral.
00:37
So first we'll substitute in 7 pi or 4.
00:40
So we get negative cosine of 7 pi over 4 plus sine of 7 pi over 4.
00:51
And then we will subtract that by substituting in negative pi over 4.
01:01
So we get negative cosine of negative pi or 4 plus.
01:05
Sine of negative pi over 4.
01:11
And now we can use our knowledge of trigonometry in the unit circle to realize that cosine of 7 pi over 4 is just square root of 2 over 2...