vikas askiitian expert
Last Activity: 14 Years ago
I = tanxtan2xtan3xdx ..............1
tan3x = tan(x+2x) = tanx + tan2x/1-tanxtan2x
tan3x(1-tanxtan2x) = tanx + tan2x
tanxtan2xtan3x = tan3x - tanx - tan2x .................2
from 1 & 2
I =( tan3x -tanx -tan2x )dx
I = logsec3x/3 - logsec2x/2 - logsecx + C
=log[ (sec3x)1/3/(sec2x)1/2(secx) ] + C
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