Circle Geometry – Lesson Plan 1 - Grade 9 Math Standard (Most curricula around the world)

What is a circle? 

Circle is a round path, the condition for each and every point of this path is to be at a certain fixed distance from a central point. The central point is called the centre of the circle and the fixed distance from centre to the path is called the radius of the circle. 

There are many practical examples of circles in daily life, such as 

1. A bracelet 
2. A cow leashed to a pole and moving around it with the leash fully stretched. 
3. Bullock path while tied to a wooden log which shift the power through gears to pull the water out of a well (older way of irrigation)

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Mathematical definition of a circle:  Circle is the locus (path) of all the points which are at a fixed distance from a given fixed point. The given fixed point is called the center of the circle and the fixed distance is called the radius of the circle. Hence the circle is fully defined by its centre (O) and the radius (r).    

Circle Geometry: