Complex Numbers And Quadratic Equations question 377

Question: If $ w=\frac{z}{z-\frac{1}{3}i} $ and $ |w|=1 $ , then z lies on [AIEEE 2005]

Options:

A) A straight line

B) A parabola

C) An ellipse

D) A circle

Show Answer

Answer:

Correct Answer: A

Solution:

$ | \frac{z}{z-\frac{i}{3}} |=1\Rightarrow |z|=| z-\frac{i}{3} | $ Clearly locus of z is perpendicular bisector of line joining points having complex number $ 0+i0 $ and $ 0+\frac{i}{3} $ . Hence z lies on a straight line.