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Question
Mathematics
Statement I Let z1 and z2 be two complex numbers such that overlinez1+i overlinez2=0 and arg (z1 ⋅ z2)=π, then arg (z1) is (3 π/4). Statement II arg (z1 ⋅ z2)= arg z1+ arg z2.
Q.
Statement I
Let
z
1
and
z
2
be two complex numbers such that
z
1
+
i
z
2
=
0
and
ar
g
(
z
1
⋅
z
2
)
=
π
, then
ar
g
(
z
1
)
is
4
3
π
.
Statement II
ar
g
(
z
1
⋅
z
2
)
=
ar
g
z
1
+
ar
g
z
2
.
539
168
Complex Numbers and Quadratic Equations
Report Error
A
Statement I is correct
B
Statement II is correct
C
Both are correct
D
Neither I nor II is correct
Solution:
Given that,
z
1
+
i
z
2
=
0
z
1
=
i
z
2
, i.e.,
z
2
=
−
i
z
1
Thus,
ar
g
(
z
1
z
2
)
=
ar
g
z
1
+
ar
g
(
−
i
z
1
)
=
π
∵
ar
g
(
z
1
z
2
)
=
ar
g
z
1
+
ar
g
z
2
⇒
ar
g
(
−
i
z
1
2
)
=
π
⇒
ar
g
(
−
i
)
+
2
ar
g
(
z
1
)
=
π
⇒
2
−
π
+
2
ar
g
(
z
1
)
=
π
⇒
ar
g
(
z
1
)
=
4
3
π