ABSTRACT
Knowledge of calculations involving circles is needed with crank mechanisms, with determinations of latitude and longitude, with pendulums, and even in the design of paper clips. The floodlit area at a football ground, the area an automatic garden sprayer sprays and the angle of lap of a belt drive all rely on calculations involving the arc of a circle. This chapter aims to define a circle and examines the state some properties of a circle – including radius, circumference, diameter, semicircle, quadrant, tangent, sector, chord, segment and arc. It explores the angle in a semicircle is a right angle an describes a radian, and change radians to degrees, and vice versa and also aims to determine arc length, area of a circle and area of a sector of a circle. The chapter discusses properties of circles are listed; arc lengths are calculated, together with more practical examples on areas of sectors of circles.
