00:01
This question, we have to consider the function in the interval of 0 to 2 pi.
00:04
And for this function, we need to find an open interval on which the function is increasing, it's increasing, and the first derivative test to identify the relative x stream loss.
00:12
And then we need to use a graphical utility to confirm our results.
00:15
So first let's try to simplify fx.
00:18
So fx is given as sine x, cos x, sine x, cos x plus 5, and using a double angle identity.
00:25
And how do we use that? we multiply by 2 and we divide by 2.
00:28
And multiplying and dividing by the same non -zero constant doesn't really change anything.
00:33
So 2x, cost x is a double angle identity which can be written as sine 2x.
00:37
So that's sine 2x over 2 plus 5.
00:39
That is fx.
00:42
Now definitely in order to find increasing or decreasing or even the relative extremis, we find f prime x.
00:47
That's going to be 1 over 2 times 2 cost 2x plus 0...