let f(a) =∫_(π/4) ^(π/3) (√(a+tan^2 x))dx with a>0
1) find a explicit form of f(a)
2) find also g(a) =∫_(π/4) ^(π/3) (dx/(√(a+tan^2 x)))
3) find the values of ∫_(π/4) ^(π/3) (√(2+tan^2 x))dx and ∫_(π/4) ^(π/3) (dx/(√(3+tan^2 x)))
we want to find the vslue of
I =∫_0 ^1 ((ln(1+x))/(1+x^2 )) dx let
A=∫∫_W (x/((1+x^2 )(1+xy)))dxdy
with W=[0,1]^2
calculate A by two method and
conclude the value of I .