00:01
So if i'm going from the second derivative to the original, then this is what's known as the anti -derivative, or i'm taking the integral of each derivative.
00:15
Then i'm taking the anti -integral of each to get to the next.
00:17
So i'm going to take the anti -derivative here to get to f -prime of theta.
00:23
So this means i'm going to take the anti -derivative with respect to d -theta, anti -derivative of sign.
00:31
What's the opposite of sign? well, recall that the derivative of sine of x is cosine of x, and the derivative of cosine is negative sine of x.
00:50
So if i'm going backwards, the anti -derivative of sign, technically this would mean the derivative of negative cosine of x is negative negative sign of x or sign of x, which means the anti -derivative of sign is negative cosine.
01:04
So this will be negative cosine of theta.
01:07
Plus antide derivative of cosine, going backwards, is just positive sign.
01:13
And this equals plus a constant c.
01:17
And this is why i'm given f prime of 0 equals 2.
01:22
So this means when i plug in 0 into my function, so negative cosine of 0 plus sine of 0, i don't know what c is yet, equals my output 2.
01:33
What's cosine at 0? well, cosine of 0 is just 1.
01:38
So this would be negative 1.
01:40
Sided 0 is just 0 plus c...