Given four points
on a circle such that
is a diameter and
is not a diameter. Show that the line joining the point of intersection of the tangents to the circle at the points
and
with the point of intersection of the lines
and
is perpendicular to the line
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Given four points $A,$ $B,$ $C,$ $D$ on a circle such that $AB$ is a diameter and $CD$ is not a diameter. Show that the line joining the point of intersection of the tangents to the circle at the points $C$ and $D$ with the point of intersection of the lines $AC$ and $BD$ is perpendicular to the line $AB.$