1.

The value of `int_(-pi//2)^(pi//2)(sin^(2)x)/(1+2^(x))dx` isA. `pi//4`B. `pi//8`C. `pi//2`D. `4pi`

Answer» Correct Answer - A
`I=int_(-pi//2)^(pi//2) (sin^(2)x)/(1+2^(x))dx`…………….i
or `I=int_(-pi//2)^(pi//2) (sin^(2)(-x))/(1+2^(-x))dx`
or `I=int_(-pi//2)^(pi//2) (2^(x).sin^(2)x)/(2^(x)+1)dx`……………ii
Adding i and ii we get
`2I=int_(-pi//2)^(pi//2) sin^(2)xdx=2int_(0)^(pi//2) sin^(2)xdx`
`=int_(0)^(pi//2)(1-cos^(2)x)dx`
`=[x-(sin2x)/2]_(0)^(pi//2)=(pi)/2`
`:. I=(pi)/4`


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