Q.

The number of values of z ∈ C, satisfying the equations |z–(4+8i)|=10 and |z–(3+5i)|+|z–(5+11i)|=45, is :          [2026]

1 0  
2 2  
3 1  
4 4  

Ans.

(2)

|z–(4+8i)|=10

It is a circle with center (4, 8) and radius = 10

|z–(3+5i)|+|z–(5+11i)|=45

It is an ellipse with focii S(3, 5) and S'(5, 11)

SS'=4+36=40=210

Clearly 45>SS'

Center of ellipse (3+52,5+112)≡(4,8) coincides with center of circle.

Now, 2a=45 ⇒ a=25

       b2=a2–c2 ⇒ b2=20–10=10

⇒ b=10 = radius of circle

∴ Ellipse and circle will intersect at end points of minor axis.

So, 2 points of intersection.