Complex Numbers And Quadratic Equations question 365

Question: The locus represented by $ |z-1|=|z+i| $ is [EAMCET 1991]

Options:

A) A circle of radius 1

B) An ellipse with foci at $ (1,0) $ and (0, - 1)

C) A straight line through the origin

D) A circle on the line joining $ (1,0),(0,1) $ as diameter

Show Answer

Answer:

Correct Answer: C

Solution:

$ |z-1|=|z+i| $
Þ $ |x-1+iy{{|}^{2}}=|x+i(y+1){{|}^{2}} $
Þ $ {{(x-1)}^{2}}+y^{2}=x^{2}+{{(y+1)}^{2}} $
Þ $ x+y=0 $ i.e., a straight line through the origin.