Intersecting Circles and a Right Angle

Let A, B, C, and D be points on a circle with center O. Let the lines AB and CD meet at M. Let the circumcircles of AOC and DOB meet at K apart from O. Then is .
Drag the light blue points or the slider to change the figure.



  • [Snapshot]
  • [Snapshot]
  • [Snapshot]


See a problem from Russia 1995.
    • Share:

Embed Interactive Demonstration New!

Just copy and paste this snippet of JavaScript code into your website or blog to put the live Demonstration on your site. More details »

Files require Wolfram CDF Player or Mathematica.