1

### IIT-JEE 2003 Screening

If $$\,\left| z \right| = 1$$ and $$\omega = {{z - 1} \over {z + 1}}$$ (where $$z \ne - 1$$), then $${\mathop{\rm Re}\nolimits} \left( \omega \right)$$ is
A
0
B
$$- {1 \over {{{\left| {z + 1} \right|}^2}}}$$
C
$$\left| {{z \over {z + 1}}} \right|.{1 \over {{{\left| {z + 1} \right|}^2}}}$$
D
$$\,{{\sqrt 2 } \over {{{\left| {z + 1} \right|}^2}}}$$
2

### IIT-JEE 2002

Let $$\omega$$ $$= - {1 \over 2} + i{{\sqrt 3 } \over 2},$$ then the value of the det.
$$\,\left| {\matrix{ 1 & 1 & 1 \cr 1 & { - 1 - {\omega ^2}} & {{\omega ^2}} \cr 1 & {{\omega ^2}} & {{\omega ^4}} \cr } } \right|$$ is
A
$$3\omega$$
B
$$3\omega \left( {\omega - 1} \right)$$
C
$$3{\omega ^2}$$
D
$$3\omega \left( {1 - \omega } \right)$$
3

### IIT-JEE 2002 Screening

For all complex numbers $${z_1},\,{z_2}$$ satisfying $$\left| {{z_1}} \right| = 12$$ and $$\left| {{z_2} - 3 - 4i} \right| = 5,$$
the minimum value of $$\left| {{z_1} - {z_2}} \right|$$ is
A
0
B
2
C
7
D
17
4

### IIT-JEE 2001 Screening

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
$$4k$$

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