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Mathematics 16 Online
OpenStudy (maheshmeghwal9):

Plz help with this: -

OpenStudy (maheshmeghwal9):

\[\tan [i \log_e{\frac{a-ib}{a+ib}}]\]

OpenStudy (maheshmeghwal9):

Simplify: -

OpenStudy (maheshmeghwal9):

Answer is : - \[\frac{2ab}{a^2-b^2}.\]

OpenStudy (maheshmeghwal9):

It is a complex number problem.

OpenStudy (maheshmeghwal9):

@TuringTest @Zarkon @myininaya Plz help

OpenStudy (anonymous):

you can write any complex number in the form: \[z=x+iy=r e^{i \theta}\]

OpenStudy (anonymous):

you got \[a-ib/a+ib=(a-ib)(a+ib)/a^2+b^2\] if you multiply and divide by conjugate

OpenStudy (anonymous):

\[\frac{a-ib}{a+ib}=\frac{(a-ib)(a-ib)}{(a+ib)(a-ib)}=\frac{a^2-b^2-2abi}{a^2+b^2}\]

OpenStudy (maheshmeghwal9):

k:) I will do it nw:)

OpenStudy (anonymous):

and you gey doing the above product the expresion mukushla said

OpenStudy (anonymous):

get*

OpenStudy (anonymous):

\[\frac{a^2-b^2-2abi}{a^2+b^2}=\frac{a^2-b^2}{a^2+b^2}-\frac{2ab}{a^2+b^2}i \]

OpenStudy (anonymous):

and for the last one \[r=\sqrt{(\frac{a^2-b^2}{a^2+b^2})^2+(\frac{-2ab}{a^2+b^2})^2}=1\]

OpenStudy (anonymous):

and \[\theta=\tan ^{-1} (\frac{-2ab}{a^2-b^2})=-\tan ^{-1} (\frac{2ab}{a^2-b^2})\]

OpenStudy (maheshmeghwal9):

I gt this much: - \[\tan [\log_e{(\frac{re^{ -i \theta}}{re^{i \theta}})^i]}\]

OpenStudy (maheshmeghwal9):

if a+bi = re^i theta

OpenStudy (anonymous):

put them in exponential form after you separate imaginary and real part, and it will be easier

OpenStudy (experimentx):

\[ \ln(a + ib) = \ln(a^2 + b^2) + i \arctan \left (\frac b a \right ) --(1)\] \[ \ln(a - ib) = \ln(a^2 + b^2) - i \arctan \left (\frac b a \right ) -- (2)\] \[ (1) -(2) = 2i\arctan \left (\frac b a \right ) -- (3)\]

OpenStudy (maheshmeghwal9):

So i get \[\tan [\log_e {\frac{e^\theta}{e^{- \theta}}}]\]

OpenStudy (maheshmeghwal9):

from my way

OpenStudy (maheshmeghwal9):

can plz anyone do from my way?

OpenStudy (maheshmeghwal9):

oh ya i gt this \[\tan( 2 \theta)\]& \[\theta = \tan ^{-1}(\frac{b}{a}.)\]

OpenStudy (maheshmeghwal9):

now what?

OpenStudy (experimentx):

sorry, it was (2) - (1) = \[ (2) -(1) = -2i\arctan \left (\frac b a \right ) -- (3)\] \[ (3) \times i = 2\arctan \left (\frac b a \right )\] \[ \tan \left( 2\arctan \left (\frac b a \right ) \right) = \frac{2ab}{a^2 - b^2}\]

OpenStudy (maheshmeghwal9):

@experimentX Plz plz will u explain my way further:)

OpenStudy (experimentx):

first step: \[ \ln \left ( a - ib \over a + ib \right) = \ln( a - ib) - \ln(a + ib) \] now follow from what i posted first.

OpenStudy (anonymous):

\[\tan(2\theta)=\frac{2tan \theta}{1-tan^2 \theta} \\ \theta=tan^{-1} \frac{b}{a} \\ so \ \ \frac{2tan \theta}{1-tan^2 \theta}=\frac{2b/a}{1-b^2/a^2}=\frac{2ab}{a^-b^2}\]

OpenStudy (experimentx):

\[ \tan 2 \theta = \frac{2\tan\theta }{1 - \tan^2\theta }\]

OpenStudy (maheshmeghwal9):

Oh ya i gt it:) thanx:)

OpenStudy (maheshmeghwal9):

to alll:_)

OpenStudy (maheshmeghwal9):

I mean:)

OpenStudy (experimentx):

yw

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