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`int_(0)^(pi)(x tanx)/(sec x +tan x)dx` |
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Answer» माना `I=int_(0)^(pi)(x tan x)/(sec x+ tanx)dx" …(1)"` `rArr" "I=int_(0)^(pi)((pi-x)tan(pi-x))/(sec(pi-x)+tan(pi-x))dx` `" "` [ प्रगुण (4 ) से ] `=int_(0)^(pi)(-(pi-x)tanx)/(-secx-tanx)dx` `rArr" "I=int_(0)^(pi)((pi-x)tanx)/(secx+tanx)dx" ...(2)"` समीकरण (1 ) और (2 ) को जोड़ने पर `2I=int_(0)^(pi)(x tanx +(pi-x)tanx)/(secx+tanx)dx` `=int_(0)^(pi)(pi tan x)/(secx+tanx)dx` `=pi int_(0)^(pi)(tanx(secx - tanx))/(sec^(2)x-tan^(2)x)dx` `=piint_(0)^(pi)(tanxsecx-tan^(2)x)dx` `=pi int_(0)^(pi)(tanx sec x - sec^(2)x+1)dx` `=pi[secx - tanx+x]_(0)^(pi)` `=pi[(secpi-tanpi+pi)-(sec 0 - tan0+0)]` `=pi[-1-0+pi-1-0+0]` `=pi(pi-2)` `rArr" "I=pi((pi)/(2)-1)` |
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