Question 983406
*[illustration chord1].


For the smaller circle AC is the tangent at point B

Therefore AB is perpendicular to AC. ( Tangent -radius)

Now for the larger circle AC is the chord and OB is perpendicular to AC at B.

therefore AB = BC . ( A line drawn perpendicular to a chord from the centre bisects the chord)

Therefor B is the mid point AC the chord.