# Circles g7

Post on 12-Jan-2015

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<ul><li> 1. Circles <br /></li></ul>
<p> 2. What is the circle?<br />The set of all points those are equidistant from a fixed point is called a circle.<br />The fixed is called center of the circle.<br />The line segment between two points on the circle which is passing through the center is called the diameter.<br />The line segment between any point on the circle and the center is called the radius (plural radii).<br /> 3. circle<br />radius<br />diameter<br />The fixed point<br />(center)<br /> 4. 5. Circumference:<br />The circumference is the length of the outer boundary of a circle.<br />circumference<br /> 6. Finding the circumference<br />The circumference of a circle is given by the formula C = D, where C is the circumference and D is the diameter of a circle.<br />Notice that D = 2xRadius = 2r<br /> : an irrational number which is approximately equal to 3.14.<br /> 7. Example:<br />Find the circumference of each of the following circles.<br /> 8. Find the circumference of each of these circles.<br /> 9. Find the perimeter of each of the shapes below. (Remember to add the lengths of the straight sections.)<br /> 10. A scooter tire has a diameter of 32 cm. What is the perimeter of the tire?<br />Find the circumference of the Ferris wheel shown below.<br /> 11. 12. Area of a circle<br />If the circle is divided into smaller sectors, the curved sides of the sectors become straighter and, hence, the shape is closer to a perfect rectangle.<br /> 13. Finding the area of a circle<br />The area of a circle, A, can be found using the formula A = r2 , where is a constant with a value of approximately 3.14 and r is the radius of the circle.<br /> 14. Example:<br />Find the area of each of the following circles.<br /> 15. Find the area of each of these circles.<br /> 16. Find the area of each of the shapes below. <br /> 17. Definition: An annulus (plural annuli) is the shape formed between two circles with a common center (called concentric circles).<br /> 18. Find the area of the annulus for the following sets of concentric circles.<br /> 19. Find the area of the following shapes:<br /></p>

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