∫tan1/3 x dx Take tanx = z ; sec2x dx = dz i.e dx = dz/(1+z2)
Putting t = 0, in the above,
B+D = 0 ............ (1)
Putting t = 1,
A + 2C + D = 1 ........... (2)
Putting t = -1,A + 2C-D = 1 ............ (3)
Using (2) & (3), D = 0
Therefore, B = 0 using (1)
A + 2C = 1 ................. (4)
