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Evaluate:`int1/(4cos^2x+9sin^2x)dx` |
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Answer» `int(1/cos^2x)/(4+(9sin^2x)/(cos^2x))dx` Let`t=tanx` `dt=secc^2xdx` `intsec^2x/(4+9tan^2x)dx` `intdt/(4+9t^2)` `1/9*int(dt)/(4/9+t^2)` `1/9*3/2*tan^(-1)(t/(2/3))+c` `1/6*tan^(-1)((3t)/2)+c` `1/6*tan^(-1)((3tanx)/2)+c`. |
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