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Category: Integration

sin-4-xdx-

Question Number 20389 by tammi last updated on 26/Aug/17 sin4xdx Answered by Joel577 last updated on 26/Aug/17 I=(1cos2x2)2dx$$\:\:\:\:=\:\frac{\mathrm{1}}{\mathrm{4}}\:\int\:\left(\mathrm{1}\:−\:\mathrm{2cos}\:\mathrm{2}{x}\:+\:\mathrm{cos}^{\mathrm{2}} \:\mathrm{2}{x}\right)\:{dx}…

sin-pxcos-qxdx-

Question Number 20387 by tammi last updated on 26/Aug/17 sinpxcosqxdx Answered by mrW1 last updated on 26/Aug/17 sin(p+q)x=sinpxcosqx+cospxsinqxsin(pq)x=sinpxcosqxcospxsinqx$$\Rightarrow\mathrm{sin}\:\mathrm{px}\:\mathrm{cos}\:\mathrm{qx}=\frac{\mathrm{1}}{\mathrm{2}}\left[\mathrm{sin}\:\left(\mathrm{p}+\mathrm{q}\right)\mathrm{x}+\mathrm{sin}\:\left(\mathrm{p}−\mathrm{q}\right)\mathrm{x}\right] \