1
IIT-JEE 2001 Screening
+2
-0.5
Let $${z_1}$$ and $${z_2}$$ be $${n^{th}}$$ roots of unity which subtend a right angle at the origin. Then $$n$$ must be of the form
A
$$4k + 1$$
B
$$4k + 2$$
C
$$4k + 3$$
D
$$4k$$
2
IIT-JEE 2001 Screening
+2
-0.5
The complex numbers $${z_1},\,{z_2}$$ and $${z_3}$$ satisfying $${{{z_1} - {z_3}} \over {{z_2} - {z_3}}} = {{1 - i\sqrt 3 } \over 2}\,$$ are the vertices of a triangle which is
A
of area zero
B
right-angled isosceles
C
equilateral
D
obtuse-angled isosceles
3
IIT-JEE 2000 Screening
+2
-0.5
If $$\arg \left( z \right) < 0,$$ then $$\arg \left( { - z} \right) - \arg \left( z \right) =$$
A
$$\pi$$
B
$$- \pi$$
C
$$- {\pi \over 2}$$
D
$${\pi \over 2}$$
4
IIT-JEE 2000 Screening
+2
-0.5
If $${z_1},\,{z_2}$$ and $${z_3}$$ are complex numbers such that $$\left| {{z_1}} \right| = \left| {{z_2}} \right| = \left| {{z_3}} \right| = \left| {{1 \over {{z_1}}} + {1 \over {{z_2}}} + {1 \over {{z_3}}}} \right| = 1,$$ then $$\left| {{z_1} + {z_2} + {z_3}} \right|$$ is
A
equal to 1
B
less than 1
C
greater than 3
D
equal to 3
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