Brianchon's theorem says:
When a hexagon is circumscribed around a conic section, its principal diagonals (those connecting opposite vertices) meet in a single point.
From interactive demo: (found at www.cut-the-knot.org)
The problem is to prove following special case:
When a hexagon is circumscribed around a circle, its principal diagonals meet in a single point.
However, the requirement is to use inversion.
I don't have the right idea, could you help?