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Question Number 133016 by metamorfose last updated on 18/Feb/21

∫_0 ^(π/2) (tan(x))^(1/n) dx ...

0π2(tan(x))1ndx...

Answered by Ar Brandon last updated on 18/Feb/21

I=∫_0 ^(π/2) (tanx)^(1/n) dx=∫_0 ^(π/2) (sinx)^(1/n) (cosx)^(−(1/n)) dx     =(1/2)Γ(((n+1)/(2n)))Γ(((n−1)/(2n)))=(1/2)∙(π/(sin(((n+1)/(2n))π))) , n>1

I=0π2(tanx)1ndx=0π2(sinx)1n(cosx)1ndx=12Γ(n+12n)Γ(n12n)=12πsin(n+12nπ),n>1

Answered by Dwaipayan Shikari last updated on 18/Feb/21

∫_0 ^(π/2) ((tanx))^(1/n)  dx=((Γ((1/2)−(1/(2n)))Γ((1/2)+(1/(2n))))/2)=(π/(2sin((π/2)+(π/(2n)))))

0π2tanxndx=Γ(1212n)Γ(12+12n)2=π2sin(π2+π2n)

Answered by mathmax by abdo last updated on 20/Feb/21

I =∫_0 ^(π/2) (tanx)^(1/n)  dx changement  tanx =t give  I =∫_0 ^∞     (t^(1/n) /(1+t^2 ))dt  =_(t=z^(1/2) )   ∫_0 ^∞     (z^(1/(2n)) /(1+z))(1/2)z^(−(1/2)) dz =(1/2)∫_0 ^∞  (z^((1/(2n))+(1/2)−1) /(1+z))dz  =(1/2)(π/(sin(π((1/(2n))+(1/2))))) =(π/(2sin((π/(2n))+(π/2)))) =(π/(2cos((π/(2n)))))(with n>1)

I=0π2(tanx)1ndxchangementtanx=tgiveI=0t1n1+t2dt=t=z120z12n1+z12z12dz=120z12n+1211+zdz=12πsin(π(12n+12))=π2sin(π2n+π2)=π2cos(π2n)(withn>1)

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