I've been studying for a integration and volumes test. I can do most of them but these few are giving me headaches. You don't have to solve them for me, just tell me what I need to do. Any help is appreciated.
1)
I know I need to substitute
=
I don't know how to go on from here.
The answer is
2)
I've tried letting , but got nowhere from that.
3)
no clue
For the first one by trig sub we get
Let
This means that
Imputting this we get
Now to integrate that thing
Ok so we do this
remember that
So subbing this in remember waht this is actually equal to we get
Now evaluating the integral within their we let
and let
So
and
Applying parts we get
Putting this back into the integral we get
Dividing both sides by two we get
Now remembering that
we need to imput back in...so seeing that
and that
wee see that
Which equals your answer