Question

The radius of the circle $\left| \frac{z - i}{z + i} \right|$= 5 is given by-

• A. $\frac{13}{12}$
• B. $\frac{5}{12}$
• C. 5
• D. 625

Answer 1

Answer: (B)

$\frac{5}{12}$

Answer 2

Sol. |z – i| = 5|z + i| Put z = x + iy & get eqn. of circle.

24x²+24y²+52y+24=0 Ž 6x²+6y²+13y+6=0

radius $\sqrt{g^{2} + f^{2} - c}$= $\frac{5}{12}$