Question

If the common chord of the circles x² + (y – b)² = 16 and x² + y² = 16 subtends a right angle at the origin then b =

(a) 4

(b) 4√2

(c) –4√2

(d) 8

Answer 1

The equation of common chord is

The combined equation of the straight lines joining the origin to the points of intersection y = b/2 and 

This equation represents a pair of perpendicular lines