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`int(1)/(tanx+cotx+secx+"cosec "x)dx` is equal toA. `(1)/(2)(sinx+cosx+x)+C`B. `(1)/(2)(sinx-cosx-x)+C`C. `(1)/(2)(cosx-xsinx)+C`D. none of these |
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Answer» Correct Answer - d Let `=int(1)/(tanx+cotx+secx+"cosec " x)dx` Then , `I=int(sinxcosx)/(1+sinx+cosx)dx` `rArrI=(1)/(2)int((1+2sinx cosx-1))/(1+sinx+cosx)dx=(1)/(2)int((sinx+cosx)^(2)-1)/(1+sinx+cosx)` `rArr I=(1)/(2)int((sinx+cosx+1)(sinx+cosx-1))/(1+sinx+cosx)dx` `rArr I=(1)/(2)int(sinx+cosx-1)dx` `rArrI=(1)/(2)(-cosx+sinx-1)+C` |
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