Complex Numbers And Quadratic Equations question 363

Question: The locus of $ z $ given by $ | \frac{z-1}{z-i} |=1 $ , is [Roorkee 1990]

Options:

A) A circle

B) An ellipse

C) A straight line

D) A parabola

Show Answer

Answer:

Correct Answer: C

Solution:

$ | \frac{z-1}{z-i} |=1 $ Þ $ |z-1|=|z-i| $
Þ $ |(x-1)+iy|=|x+i(y-1)| $
Þ $ \sqrt{{{(x-1)}^{2}}+y^{2}}=\sqrt{x^{2}+{{(y-1)}^{2}}} $
Þ $ 2x=2y $ or $ x-y=0 $ Which is the equation of a straight line.