Tuesday, March 17, 2015

Grade 7 : CIRCLES

From earliest times the circle has fascinated people around the world. 
The sun and moon (both apparently circles) have been worshipped. From early Greek times the circle has been studied and now position on the Earth's surface is described in terms of intersecting circles. As a result of all of this interest, the parts of a circle have been carefully named. 
It is important to know what the different parts of a circle are called. They are summarised in the table below: 







CIRCUMFERENCE OF A CIRCLE
It is usually easier to measure the diameter of a circle than its circumference. Obviously the larger the diameter of a circle, the greater its circumference.
Students do some investigation to discover the special relationship that exist between the circumference of a circle and its diameter







From the investigation, they can conclude that for all circles :
Length of Circumference (C) : Length of diameter (d) = 3.142
Because this number is very special it is given the symbol pi

Resources : International Mathematics 2 For the Middle Years Chapter 12 Circles

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