Question Number 54093 by Tawa1 last updated on 28/Jan/19
$$\mathrm{If}\:\:\:\:\:\:\mathrm{tan}\left(\mathrm{z}\right)\:\:=\:\:\mathrm{2},\:\:\:\:\mathrm{find}\:\mathrm{the}\:\mathrm{value}\:\mathrm{of}\:\:\mathrm{z} \\ $$
Commented by mr W last updated on 28/Jan/19
$${z}=\mathrm{tan}^{−\mathrm{1}} \mathrm{2}+{n}\pi \\ $$
Commented by Tawa1 last updated on 29/Jan/19
$$\mathrm{God}\:\mathrm{bless}\:\mathrm{you}\:\mathrm{sir}.\:\:\mathrm{But}\:\mathrm{sir},\:\:\:\mathrm{z}\:=\:\mathrm{x}\:+\:\mathrm{iy},\:\:\mathrm{is}\:\mathrm{it}\:\mathrm{the}\:\mathrm{same}\:\mathrm{thing}\:? \\ $$
Commented by mr W last updated on 29/Jan/19
$${z}={x}+{y}\:{i} \\ $$$$\mathrm{tan}\:{z}=\frac{\mathrm{sin}\:\left(\mathrm{2}{x}\right)+{i}\:\mathrm{sinh}\:\left(\mathrm{2}{y}\right)}{\mathrm{cosh}\:\left(\mathrm{2}{y}\right)+\mathrm{cos}\:\left(\mathrm{2}{x}\right)}=\mathrm{2} \\ $$$$\mathrm{sinh}\:\left(\mathrm{2}{y}\right)=\mathrm{0}\Rightarrow{y}=\mathrm{0} \\ $$$$\mathrm{sin}\:\left(\mathrm{2}{x}\right)=\mathrm{2}\:\left[\mathrm{cosh}\:\left(\mathrm{2}{y}\right)+\mathrm{cos}\:\left(\mathrm{2}{x}\right)\right] \\ $$$$\mathrm{2}\:\mathrm{sin}\:{x}\:\mathrm{cos}\:{x}=\mathrm{2}\:\left[\mathrm{1}+\mathrm{2cos}^{\mathrm{2}} \:{x}−\mathrm{1}\right] \\ $$$$\mathrm{sin}\:{x}=\mathrm{2cos}\:{x} \\ $$$$\mathrm{tan}\:{x}=\mathrm{2}\Rightarrow{x}=\mathrm{tan}^{−\mathrm{1}} \mathrm{2}+{n}\pi \\ $$$$\Rightarrow{z}=\mathrm{tan}^{−\mathrm{1}} \mathrm{2}+{n}\pi+\mathrm{0}{i} \\ $$
Commented by Tawa1 last updated on 29/Jan/19
$$\mathrm{God}\:\mathrm{bless}\:\mathrm{you}\:\mathrm{sir},\:\mathrm{i}\:\mathrm{appreciate}.\: \\ $$
Commented by Tawa1 last updated on 29/Jan/19
$$\mathrm{Please}\:\mathrm{sir}.\:\:\mathrm{How}\:\mathrm{is}\:\mathrm{cosh}\left(\mathrm{2y}\right)\:=\:\mathrm{1}\:\:\mathrm{sir}\:\:\:\:\mathrm{from}\:\:\:\mathrm{cosh}\left(\mathrm{2y}\right)\:+\:\mathrm{cos}\left(\mathrm{2x}\right) \\ $$
Commented by Tawa1 last updated on 29/Jan/19
$$\mathrm{Ohh},\:\mathrm{i}\:\mathrm{get}.\:\:\mathrm{Since}\:\:\mathrm{y}\:=\:\mathrm{0}\:\:\mathrm{right}\:? \\ $$
Commented by mr W last updated on 29/Jan/19
$${yes} \\ $$
Commented by Tawa1 last updated on 29/Jan/19
$$\mathrm{Thanks}\:\mathrm{sir} \\ $$