Y by Adventure10, Mango247
Let
be a point in the exterior of a circle of center
, and let
be the points where the tangents from
touch the circle. Let
be an arbitrary point on the small arc
. The tangent in
at the circle intersects the line
in
, and the lines
and
intersect in
. We denote by
the intersection of the lines
and
.
Prove that the lines
and
are perpendicular.















Prove that the lines

