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please solve this
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hii let us first try to simplify the expression ... so (cos5x + cos4x)/(1 - 2cos3x) = (2cos(9x/2).cos(x/2))/(1 - 2cos3x) = (2cos(9x/2).cos(x/2))/( 1 - 2.(2cos2(3x/2) - 1) ) = (2cos(9x/2).cos(x/2))/(3 - 4.cos2(3x/2)) = (2.(4.cos3(3x/2) - 3cos(3x/2)).cos(x/2))/(3 - 4.cos2(3x/2)) = -2.cos(3x/2)cos(x/2) = -( cos2x + cosx ) so now the integral is -sin(2x)/2 - sinx + c cheers |
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Puneet Agrawal IIT Delhi |
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