Q.

The value of e-π4+0π4e-xtan50xdx0π4e-x(tan49x+tan51x)dx is:            [2023]

1 51  
2 49  
3 25  
4 50  

Ans.

(4)

e-π/4+0π/4e-xtan50xdx0π/4e-x(tan49x+tan51x)dx

First, simplify, 0π/4e-xtan50xdx

=[-e-x(tanx)50]0π/4+0π/4e-x(50)tan49x·sec2xdx

=-e-π/4+0+500π/4e-x(tanx)49(1+tan2x)dx

=-e-π/4+500π/4e-x[(tanx)51+(tanx)49]dx

Now, -e-π/4+0π/4e-x(tanx)50dx0π/4e-x(tan49x+tan51x)dx

=500π/4e-x(tan51x+tan49x)dx0π/4e-x(tan49x+tan51x)dx=50

  e-π/4+0π/4e-xtan50xdx0π/4e-x(tan49x+tan51x)dx=50