The right approach to do the sums on circles is to know the basic definitions of circles and know the difference between a circle and a sphere. You will have to know the formulas and the abbreviations to solve every sum from this chapter. The best you can do is to refer to the solutions available on the educational websites, Always check the syllabus and the sums present in the solution paper for making the correct match. If you find commonality, consider the solution paper to be relevant. Once you download the right solution paper, you can start solving the sums on a regular basis.