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Joint Entrance Examination
Mathematics
Complex Numbers
Question 366
Question 366 of 455
Medium
MCQ
Let
z
z
z
and
w
w
w
be complex numbers such that
z
+
i
w
=
0
z+iw=0
z
+
i
w
=
0
and
arg
(
z
w
)
=
π
\arg(zw)=\pi
ar
g
(
z
w
)
=
π
. Then
arg
z
\arg z
ar
g
z
equals
A
5
π
4
\dfrac{5\pi}4
4
5
π
B
π
2
\dfrac\pi2
2
π
C
3
π
4
\dfrac{3\pi}4
4
3
π
D
π
4
\dfrac\pi4
4
π
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Solutions · 1
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Official solution
z
=
−
i
w
⟹
arg
z
=
π
2
+
arg
w
z=-iw \implies \arg z=\dfrac\pi2+\arg w
z
=
−
i
w
⟹
ar
g
z
=
2
π
+
ar
g
w
(adjusting branch). Also
arg
z
+
arg
w
=
π
\arg z+\arg w=\pi
ar
g
z
+
ar
g
w
=
π
. Solving:
arg
z
=
3
π
4
.
\arg z=\dfrac{3\pi}4.
ar
g
z
=
4
3
π
.
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