2006 SQA Higher Maths: paper 2 no.4: Equations of circles

Finding the centre and radius of a circle given the equation in either form. Instructional exercise consisting of question 4 from paper 2 of the 2006 SQA Higher Mathematics exam. Set out in stages of 'try then check' the worked solution to each part of the question. Including indications of where each mark is allocated, and the requirements for that mark, according to the marking scheme.