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prove-cos-B-C-A-cos-C-A-B-cos-A-B-C-cos-A-B-C-4sinAcosBsinC-

Question Number 219659 by Nicholas666 last updated on 30/Apr/25 $$ \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:{prove}; \\ $$$$\:\:{cos}\:\left({B}+{C}−{A}\right)−{cos}\left({C}+{A}−{B}\right)+{cos}\left({A}+{B}−{C}\right)−{cos}\left({A}+{B}+{C}\right)\:=\: \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\mathrm{4}{sinAcosBsinC} \\ $$$$ \\ $$ Answered by som(math1967) last updated…

Question-219685

Question Number 219685 by alcohol last updated on 30/Apr/25 Answered by SdC355 last updated on 01/May/25 $$\kappa=\frac{\mathrm{2}}{\:\sqrt{\left(\mathrm{1}+\mathrm{4}{x}^{\mathrm{2}} \right)^{\mathrm{3}} }}\:\:\:\left(\mathrm{curvature}\:\kappa=\frac{\mid\mid{y}^{\left(\mathrm{2}\right)} \left({t}\right)\mid\mid}{\:\sqrt{\left(\mathrm{1}+\left({y}^{\left(\mathrm{1}\right)} \left({t}\right)\right)^{\mathrm{2}} \right)^{\mathrm{3}} }}\:\right) \\ $$$${r}=\frac{\mathrm{1}}{\kappa}=\frac{\sqrt{\left(\mathrm{1}+\mathrm{4}{x}^{\mathrm{2}}…

0-sin-z-z-z-2-4-dz-1-4-0-sin-z-z-sin-z-2z-4i-sin-z-2z-4i-dz-and-next-2pii-j-1-M-Res-h-a-j-f-h-

Question Number 219574 by SdC355 last updated on 29/Apr/25 $$\int_{\mathrm{0}} ^{\:\infty} \:\:\frac{\mathrm{sin}\left({z}\right)}{{z}\left({z}^{\mathrm{2}} +\mathrm{4}\right)}\:\mathrm{d}{z}=\frac{\mathrm{1}}{\mathrm{4}}\int_{\mathrm{0}} ^{\:\infty} \:\:\left(\frac{\mathrm{sin}\left({z}\right)}{{z}}−\frac{\mathrm{sin}\left({z}\right)}{\mathrm{2}{z}+\mathrm{4}\boldsymbol{{i}}}−\frac{\mathrm{sin}\left({z}\right)}{\mathrm{2}{z}−\mathrm{4}\boldsymbol{{i}}}\right)\:\mathrm{d}{z} \\ $$$$\mathrm{and}\:\mathrm{next}….??? \\ $$$$\mathrm{2}\pi\boldsymbol{{i}}\underset{{j}=\mathrm{1}} {\overset{{M}} {\sum}}\:\:\mathrm{Res}_{{h}={a}_{{j}} } \left\{{f}\left({h}\right)\right\}…. \\ $$…