Question

Let C be the circle with centre at (1, 1) and radius = 1. If T is the circle centered at (0, y) passing through the origin and touching the circle C externally, then the radius of T is equal …

(a) √3/√2

(b) √3/2

(c) 1/2

(d) 1/4

Answer 1

(d) 1/4

Equation of circle is x² + y² + 2gx + 2fy + c = 0

i.e., (1 + y²)² = (1 – y)² = 1 

Solving we get y = 1/4