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Author: Tinku Tara

6-sinx-cosx-sinx-cosx-dx-

Question Number 8281 by tawakalitu last updated on 06/Oct/16 $$\int\frac{\mathrm{6}\:\mathrm{sinx}\:\mathrm{cosx}}{\mathrm{sinx}\:+\:\mathrm{cosx}}\:\mathrm{dx} \\ $$ Answered by Yozzias last updated on 06/Oct/16 $$\frac{\mathrm{sinx}}{\mathrm{sinx}+\mathrm{cosx}}=\mathrm{1}−\frac{\mathrm{cosx}}{\mathrm{sinx}+\mathrm{cosx}} \\ $$$$\therefore\:\mathrm{I}=\int\frac{\mathrm{sinxcosx}}{\mathrm{sinx}+\mathrm{cosx}}\mathrm{dx}=\int\left(\mathrm{1}−\frac{\mathrm{cosx}}{\mathrm{sinx}+\mathrm{cosx}}\right)\mathrm{cosxdx} \\ $$$$=\int\left(\mathrm{cosx}−\frac{\mathrm{cos}^{\mathrm{2}} \mathrm{x}}{\mathrm{sinx}+\mathrm{cosx}}\right)\mathrm{dx}…

Show-that-one-representation-for-pi-3-14-is-pi-12cos-1-3-4-1-4-1-r-1-k-1-2r-3-2-k-2r-1-3-r-

Question Number 8277 by Yozzias last updated on 05/Oct/16 $$\mathrm{Show}\:\mathrm{that}\:\mathrm{one}\:\mathrm{representation}\:\mathrm{for}\:\pi\approx\mathrm{3}.\mathrm{14}… \\ $$$$\mathrm{is}\:\pi=\mathrm{12cos}^{−\mathrm{1}} \left[\left(\frac{\mathrm{3}}{\mathrm{4}}\right)^{\mathrm{1}/\mathrm{4}} \left(\mathrm{1}+\underset{\mathrm{r}=\mathrm{1}} {\overset{\infty} {\sum}}\frac{\underset{\mathrm{k}=\mathrm{1}} {\overset{\mathrm{2r}} {\prod}}\left(\frac{\mathrm{3}}{\mathrm{2}}−\mathrm{k}\right)}{\left(\mathrm{2r}\right)!}\left(\frac{−\mathrm{1}}{\mathrm{3}}\right)^{\mathrm{r}} \right)\right]. \\ $$$$ \\ $$ Terms of…