for help you can see solved question in :

http://1nidhi.blogspot.com/2015/07/equation-of-circle-in-cartesian-form_19.html

http://1nidhi.blogspot.com/2015/07/equation-of-circle-in-cartesian-form.html

http://1nidhi.blogspot.com/2015/07/equation-of-circle-in-cartesian-form_19.html

http://1nidhi.blogspot.com/2015/07/equation-of-circle-in-cartesian-form.html