3
$\begingroup$

how can i determine wether a circle can be circumscribed about a quadrilateral?

  • 2
    Look at opposite angles. A convex quadrilateral is cyclic if and only if its opposite angles add up to $\pi$ ($= 180^\circ$).2011-03-14
  • 0
    See http://en.wikipedia.org/wiki/Cyclic_quadrilateral2011-03-14

1 Answers 1