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ABCD is a cyclic quadrilateral and the points A , B and C form an equilateral triangle .

Then what is the sum of the length of line segments DA and DC? What property should i use to get the value of DA and DC.

I need a hint to start the solution.

Thanks in advance.

  • 0
    What does PQRS have to do with anything? Where is D in relation to ABC?2012-04-01
  • 0
    @robjohn i am sorry.edited the question.2012-04-01
  • 0
    Hint: [Ptolemy's theorem](http://en.wikipedia.org/wiki/Ptolemy%27s_theorem).2012-04-01

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