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निम्नलिखित को सिद्ध कीजिए । `int_(0)^((pi)/(2))tan^(3)x dx = 1-log2`

Answer» माना `I=int_(0)^(pi//4)2 tan^(3)x dx`
`" "=2 int_(0)^(pi//4)tan^(2)x. tanx dx`
`" "=2int_(0)^(pi//4)(sec^(2)x-1)tanxdx`
`=2[int_(0)^(pi//4)sec^(2)x tanx dx - int_(0)^(pi//4)tanx dx]`
`=2int_(0)^(pi//4)(tanx)sec^(2)x dx-2[-log|cosx|]_(0)^(pi//4)`
`=2[(tan^(2)x)/(2)]_(0)^(pi//4)+2[log|cos.(pi)/(4)|-log|cos0|]`
`=tan^(2)((pi)/(4))-0+2[log((1)/(sqrt2))-log1]`
`=1+2log2^(-1//2)-0=1-2xx(1)/(2)log2 = 1-log2" "` यही सिद्ध करना था ।


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