Calculus quick help

[thespeakerbox]

When do i use them. They all look the same. The only clear one is washers.

 

[thespeakerbox]

ahhhh

 

[Howard]

Finding volume?

 

[Crusty]

A question would be helpful.... i don't know though, just reaching out here.

 

[thespeakerbox]

uhh. how do you integrate cos2xdx

 

[Crusty]

cos(x)sin(x)

 

[firewall]

Originally posted by: thespeakerbox
uhh. how do you integrate cos2xdx

Expand cos2x and then integrate.

 

[thespeakerbox]

i still dont got it

 

[firewall]

cos2x = cos(2)x - sin(2)x = 2cos(2)x - 1 = 1 - 2sin(2)x

(2) is power - square in this case.

 

[dighn]

they do the same thing, but depending on the situation one might be easier to do than the others

 

[Soccerman06]

Silly calc 1 student. one invovles using pi*r^2 where r is the integral of your equation i dont remember other ones.

 

[MrCodeDude]

Originally posted by: Soccerman06
Silly calc 1 student. one invovles using pi*r^2 where r is the integral of your equation i dont remember other ones.

This was Calc 2 material for me.

I absolutely hated discs, shells, washers, etc.

 

[chuckywang]

If you are having trouble with disks, shells, and washers, then you don't really understand what an "integral" does. They are all derived through a fundamental understanding of the integral.