I am'nt able to solve the questions based on normal of a circle . . I cannot really get the concept of it ! plz.. help me with a diagram because i know the equations related to it but cannot solve analytical questions based on normal form .can't really get the imagination behind the idea of normals to a circle . PLZ. HELP THANKZ IN ADVANCE ! :)

a normal to a curve at a point on the curve is defined as that line which passes through the point and is at right angles to the tangent at the point. for a circle, at any point the tangent is perpendicular to the line passing through the point in question and the centre of the circle which is nothing but a secant passing through the centre, which in turn is a diameter extended outside the circle to infinity on both sides.