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Mathematics 20 Online
OpenStudy (maheshmeghwal9):

Please simplify:) Its answer is [(2ab)/(a^2-b^2)].

OpenStudy (maheshmeghwal9):

OpenStudy (maheshmeghwal9):

here i=iota, a complex number of form (0,1).

OpenStudy (unklerhaukus):

\[\tan\left[i\log\left(\frac{a-ib}{a+ib}\right)\right]\]

OpenStudy (anonymous):

Pl start with denoting a + ib in the form r( cos x + i sin x) Then equate real and imaginary part. Try.

OpenStudy (maheshmeghwal9):

@UnkleRhaukus plz help:) & ya that is the question.

OpenStudy (unklerhaukus):

i have not studied complex analysis, and i have not done a problem like this before,

OpenStudy (maheshmeghwal9):

k! np:)

OpenStudy (maheshmeghwal9):

ya it is the answer I know; but I haven't solved it:(

OpenStudy (maheshmeghwal9):

@Mertsj plz help:)

OpenStudy (anonymous):

start with \[\log(a-bi)-\log(a+bi)\] then by definition \(\log(z)=\ln(z)+i\theta\) so you get \[\ln(\sqrt{a^2+b^2}+i\theta -(\ln(\sqrt{a^2+b^2})-i\theta)\] the last part because if arg \(a+bi=\theta\) then arg\(a-bi=-\theta\) this adds to \(2i\theta\) multiply by \(i\) get \(-2\theta\) and you want the tangent \[\tan(-2\theta=-\tan(2\theta)\] and \[\tan(\theta)=\frac{b}{a}\] so now double angle formula should give you the result i might have made a mistake in calculation, so check it, but this i am fairly sure that this is the right method

OpenStudy (anonymous):

Put a=r cosA, b==r sinA Expression= tan [i. log (cosA-i sinA)/cosA+i sinA)] =tan [i. log (e^-iA)/(e^iA)] =tan[i. log e^(-2iA)] =tan[i.(-2iA)] =tan 2A =2 tanA/(1-tan^2 A) =2.(b/a) / [1-(b/a)^2] =2ab/a^2 +b^2

OpenStudy (maheshmeghwal9):

k! thanx a lot:)

OpenStudy (anonymous):

UR welcome.

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