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4-1.Complex numbers
medium
જો $z,w$ એ સંકર સંખ્યા છે કે જેથી $\overline z + i\overline w = 0$ અને $arg\,\,zw = \pi $ તો arg z મેળવો.
A
$5\pi /4$
B
$\pi /2$
C
$3\pi /4$
D
$\pi /4$
(AIEEE-2004)
Solution
(c)Given that arg zw =$\pi $ …..$(i)$
$\bar z + i\bar \omega = 0 \Rightarrow \bar z = – i\bar \omega $$ \Rightarrow z = i\omega $$ \Rightarrow \omega = – iz$
From $(i)$, arg$( – i{z^2}) = \pi $
$arg\;( – i) + 2arg(z) = \pi $ ;
$\frac{{ – \pi }}{2} + 2\;arg(z) = \pi $
$2\,arg\,(z) = \frac{{3\pi }}{2}$;
$a\,rg(z) = \frac{{3\pi }}{4}$
Standard 11
Mathematics