Answer: The radius and the cord must be perpendicular to each other.
Step-by-step explanation:
A cord is a line from a point of circumference of a circle to another point of the circumference of the circle without passing through the centre.
A radius is a line from the centre of a circle to the circumference of the circle.
When the radius line intersect and bisects a cord of a circle, the radius and the cord must be perpendicular to each other.
