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View Full Version : Ssec^3(w)dw is very easy but you need to pay atention!


kallazans
Dec20-03, 11:46 AM
Ssec^3(w)dw
it is very easy if you use integration by parts, but you need to pay atention!

how about use a partial fraction ? if you like to have a hard work!!

Someone agree with me?

HallsofIvy
Dec20-03, 06:49 PM
Actually, the way I would do that is to write sec3w as
1/cos3(w) and sec3(w)dw as
cos(w)dw/cos4(w)= cos dw/(1- sin2(w))2, make the substitution u= sin(w) so the integral becomes
∫ du/(1-u2)2 and THEN use partial fractions. Is that what you meant?