Circles is a topic in the NCERT book for Class 9 Maths. It deals with the basic concepts and properties of circles, such as radius, diameter, chord, arc, sector, segment, angle subtended by a chord, cyclic quadrilaterals, etc. It also teaches how to construct circles and prove some theorems related to them. The chapter has three exercises with different types of questions, such as fill in the blanks, true or false, prove that, find the value of, etc. The chapter aims to develop the geometrical skills and logical thinking of the students.
