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इन समाकलनो का मान कीजिएः `int_(0)^(pi//4) sin3x sin 2xdx` |
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Answer» `underset(0)overset(pi//4)int sin3x sin 2dx` `=1/2underset(0)overset(pi//4)int (2 sin 3 x sin2x)dx` `=1/2underset(0)overset(pi//4)int (cos x-cos 5x)dx` `[therefore 2 sin A sin B=cos (A-B)-cos(A+B)]` `=1/2[sin x-(sin 5x)/(5)]_(0)^(pi//4)` `=1/2[1/sqrt2+1/5sin""(pi)/(4)]=1/2[1/sqrt2+1/(2sqrt2)]` `=(6)/(2(5sqrt2))=(3sqrt2)/(10)` |
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