A circle is a closed shape formed by tracing a point that moves in a plane such that its distance from a given point is constant. The word circle is derived from the Greek word “Kirkos”, meaning hoop or ring. Circles are the most symmetric plane figures and they possess remarkable geometric properties. In this topic, we shall explore the circle as a locus, circle theorems, tangent to a circle and alternate segment.

The knowledge of a circle is very important in solving many real-life problems. The importance of circle can be seen from the designs featured in the artefacts of ancient civilizations as well as its use in modern architecture all over the world. In this topic, we will also learn about perimeter of rectangle and square; area of parallelogram; rectangle and square; and arcs and sectors.