vikas askiitian expert
Last Activity: 14 Years ago
this q integration is too lenthy , here is the complete solution ...
I = xlog(sinx)dx .........1 lim 0 t0 pi
I =(pi-x)logsin(pi-x)dx lim 0 to pi (using property of integration)
I = -xlog(sinx)dx + pilog(sinx)dx ................2 lim 0 to pi
adding 1 & 2
2I = pilogsinxdx or
2I/pi = logsinxdx .....................3 lim 0 to pi
2Ipi = logsinxdx + logsinpi-x dx lim 0 to pi/2 (by property)
2I/PI = 2logsinx dx ................4 lim 0 to pi/2
2I/pi = 2logcosx dx ................5 lim 0 to pi/2 (by property)
adding 4 & 5
4I/pi =2log(sin2x)/2 dx lim 0 to pi/2
2I/pi = logsin2xdx - log2 dx from 0 to pi/2
2I/pi = I1 - log2dx lim 0 to pi
from this eq 6 integrating logsin2x seperately
I1 = logsin2xdx lim 0 to pi/2
put 2x =t
I1 = (logsintdt)/2 lim 0 to pi
now interchanging variable t with x
I1 = logsinxdx/2 lim 0 to pi ........................7
from eq 3 & 7
I1 = I/pi .........8
putting eq 8 in 6
then
2I/pi = I/Pi - log2dx lim 0 to pi
I/pi = -(log2)x lim 0 to pi
I/pi =-pilog2