How do I solve INT x sec^2x dx using integration by parts?

AI Thread Summary
To solve the integral INT x sec^2x dx, integration by parts is necessary, with the suggestion to set x as u and sec^2x dx as dv. The correct evaluation of the definite integral from 0 to π/4 yields the result π/4 - ln2/2. While some participants mention using the tabular method for efficiency, it is noted that this integral only requires a single integration by parts step. For those unfamiliar with integrating tan x, breaking it down into sine and cosine components with u-substitution is recommended.
ryan750
Messages
23
Reaction score
0
show that INT x sec^2x dx = pi/4 - ln2/2 (between pi/4 and 0)

pls help i don't know where to start

i know it is integration by parts - just don't know how i should rearrange it. thanks
 
Physics news on Phys.org
If you know part integration,u'll find the notation quite familiar

x=u;\sec x dx =dv

BTW,it should read

\int_{0}^{\frac{\pi}{4}} x\sec^{2} x \ dx=\frac{\pi}{4}-\frac{\ln 2}{2}

Daniel.
 
Tabular method, so much easier. Enough said.
 
Tabular method really only helps when you have several ibp steps. In this case, you only have one. Once you integrate sec^2 x, you get tan x. If you're going to integrate tan x manually (vs just looking at the table), it's easiest to break it into

\int{\sin x \frac{1}{\cos x} dx}

and then use u-substitution.
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top