Cyclic Quadrilateral

[physics kiddy]

1. The problem statement, all variables and given/known data

I have got a question that might be easy for you. But, not for me.

I have attached a pic. Please tell me if the quadrilateral inside the circle is a cyclic quadrilateral or not. If it is, then please explain how to prove that it's opposite angles sum up to 180 degrees

2. Relevant equations

I believe it won't require any equation.



3. The attempt at a solution

No idea !

[micromass]

What is the definition of a cyclic quadrilateral??

[Joffan]

As for proof, this might help: http://en.wikipedia.org/wiki/Inscribed_angle