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Author: Tinku Tara

L-lim-n-k-1-n-k-n-2-k-2-1-0-e-x-2-dx-1-m-0-1-m-2m-1-3-m-

Question Number 220764 by Nicholas666 last updated on 18/May/25 $$ \\ $$$$\:\:\boldsymbol{\mathrm{L}}=\:\boldsymbol{\mathrm{lim}}\underset{\:\boldsymbol{{n}}\rightarrow\infty} {\:}\left(\underset{\boldsymbol{{k}}=\mathrm{1}} {\overset{\boldsymbol{{n}}} {\sum}}\:\frac{\boldsymbol{{k}}}{\boldsymbol{{n}}^{\mathrm{2}} +\boldsymbol{{k}}^{\mathrm{2}} }\right).\left(\underset{\:\mathrm{0}} {\int}^{\:\mathrm{1}} \boldsymbol{{e}}^{−\boldsymbol{{x}}^{\mathrm{2}} } \boldsymbol{{dx}}\overset{−\mathrm{1}} {\right)}.\left(\underset{\boldsymbol{{m}}=\mathrm{0}} {\overset{\infty} {\sum}}\:\frac{\left(−\mathrm{1}\right)^{\boldsymbol{{m}}} }{\left(\mathrm{2}\boldsymbol{{m}}+\mathrm{1}\right)\mathrm{3}^{\boldsymbol{{m}}}…

Question-220745

Question Number 220745 by Spillover last updated on 18/May/25 Answered by som(math1967) last updated on 18/May/25 $${cosx}+{cosy}={a} \\ $$$$\Rightarrow\mathrm{2}{cos}\left(\frac{{x}+{y}}{\mathrm{2}}\right){cos}\left(\frac{{x}−{y}}{\mathrm{2}}\right)={a}…\left(\mathrm{1}\right) \\ $$$$\:{sinx}+{siny}={b} \\ $$$$\Rightarrow\mathrm{2}{sin}\left(\frac{{x}+{y}}{\mathrm{2}}\right){cos}\left(\frac{{x}−{y}}{\mathrm{2}}\right)={b}\:\:….\left(\mathrm{2}\right) \\ $$$$\therefore\:{tan}\left(\frac{{x}+{y}}{\mathrm{2}}\right)=\frac{{b}}{{a}}\:\:\:\:\:\left[\:\:\left(\mathrm{2}\right)\boldsymbol{\div}\left(\mathrm{1}\right)\:\right]…