Two equal circles of radius 18 cm intersect each other, such that each passes through the centre of the other. The length of the common chord is

The radius of each circle = 18 cm.

Each circle passes through the center of the other, meaning the distance between the centers of the circles equals the radius (18 cm). 

Concept Used: ​

if two circle intersect each other at the center,

then, length of the common chord = $$\sqrt{3}\ r$$ 

where, r is radius.

Therefore, length of the common chord AB = $$6\sqrt{3} cm$$ ​