00:01
Okay, in part a i want to show this is true.
00:03
To do that, i will let u equal sinex, which means du by dx is cosx.
00:18
For the words, dx will be 1 over cosx, du.
00:27
Let's rearrange it.
00:31
This becomes the integral of, sinex is u, leave cosx for now.
00:40
Is 1 over cos x d u so that will cancel out and we're left with the integral of u d u which is u squared over 2 plus c1 and what was u squared sine squared so it's one half of sine squared x plus c1 and that's the first one proven.
01:16
Okay, part b then is this.
01:20
And the same idea.
01:22
What i would do is i will let you now equal cos x and i work out du by dx as negative sine x which again means that dx is negative 1 over sine x du...