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If-tan-z-2-find-the-value-of-z-




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

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