Worked solution to 2013 higher level circle question. Check out KeysToMaths1 for more tutorials and solutions: https://www.youtube.com/channel/UCOYoe9L9R13HGUIhszjkeug

How to find the measure of circumscribed angles, for use in your problem solving toolkit. More free lessons at: http://www.khanacademy.org/video?v=eF6zYNzlZKQ Note: All Khan Academy content is available for free at (www.khanacademy.org)

Extracting information about the circle given its equation. More free lessons at: http://www.khanacademy.org/video?v=eF6zYNzlZKQ Note: All Khan Academy content is available for free at (www.khanacademy.org)

Completing the square to write the equation of a circle in standard form. More free lessons at: http://www.khanacademy.org/video?v=eF6zYNzlZKQ Note: All Khan Academy content is available for free at (www.khanacademy.org)

Nice tutorial for the equation of a circle.
More free lessons at: http://www.khanacademy.org/video?v=JvDpYlyKkNU
Note: All Khan Academy content is available for free at (www.khanacademy.org)