Area of cylinder by integration methods

ian.f

Doing my LC tomorrow and would love a bit of help

I can get area of circle by integration and I can also get volume of circle and cone by integration. Now I just need volume of cyclinder... Can anyone help me.

Thanks

mahamageehad

hey im not quite sure about the actual working out of it but you have to rotate a line around the x axis as far as i know

Thomas_S_Hunterson

bmcgov86 wrote: »

alrit man,
well u know the way u draw a triangle and then rotate for a cone, for the cylinder u would draw a rectangle and then rotate. the triangle would be lenght 'h' along the x axis and height 'r' (radius) along the y axis. then if u rotate it around the x axis u would get a cylinder.

You draw a line not a rectangle!!!!

So find the area when the function y=r (where r is the radius) is rotated around the x axis, between x=0 and x=h (where h will be the height of the cylinder).

ian.f

ah sound lads... thats an absolute joke, fingers crossed that it comes up!

Blackangel

can that actually come up though because i was looking at the syllabus and it says that its only the sphere and cone that are on it.

Thomas_S_Hunterson

bmcgov86 wrote: »

sean k im sorry but u are wrong there. if u draw a line u get a dimensionless object of mathematically no exsistence. it would be basically a cylinder with no centre, like a hollow tube. trust me i got an a1 a few years back, u draw a rectangle.

Let's not get into a "my qualification is better than your qualification" argument because I will win.:pac:

But you do use a line function.

The volume of rotation integral finds VOLUME of rotation.

When you rotate a line around the x axis you get a cylinder.

mahamageehad

hahahaha is dare a maths slaggin match goin on here that i wasnt invited to?? Haha

ZorbaTehZ

mahamageehad wrote: »

hahahaha is dare a maths slaggin match goin on here that i wasnt invited to?? Haha

qft, i was wondering was i the only one who couldn't see bmcgov86 posts...

btw Sean K is right

Thomas_S_Hunterson

I think he went and deleted them....after claiming to be a doctor of statistics:pac:

Michael Collins

1) This isn't on the exam syllabus so no need to bother really. It's just a cone and a sphere as Blackangel rightly said.

2) With a cylinder, you don't have to integrate it at all since the distance from the centre line is constant i.e. you just have:

volume = cross sectional area * height = pi.r^2*h = pi r^2 h

You'd only integrate when the height isn't constant like for a circle...