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Circles g7
The document defines key terms related to circles such as radius, diameter, and circumference. It provides the formulas to calculate the circumference (C = πD) and area (A = πr^2) of a circle based on the diameter or radius. Several examples are given to find the circumference or area of various circles and shapes formed by circles.
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Circles g7
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- 2. What is thecircle?The set of all points those are equidistant from a fixed point is called a circle.The fixed is called center of the circle.The line segment between two points on the circle which is passing through the center is called the diameter.The line segment between any point on the circle and the center is called the radius (plural radii).
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- 5. Circumference:The circumference isthe length of the outer boundary of a circle.circumference
- 6. Finding the circumferenceThecircumference of a circle is given by the formula C = πD, where C is the circumference and D is the diameter of a circle.Notice that D = 2xRadius = 2rπ : an irrational number which is approximately equal to 3.14.
- 7. Example:Find the circumferenceof each of the following circles.
- 8. Find the circumferenceof each of these circles.
- 9. Find the perimeterof each of the shapes below. (Remember to add the lengths of the straight sections.)
- 10. A scooter tirehas a diameter of 32 cm. What is the perimeter of the tire?Find the circumference of the Ferris wheel shown below.
- 12. Area of acircleIf 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.
- 13. Finding the areaof a circleThe area of a circle, A, can be found using the formula A = π r2 , where π is a constant with a value of approximately 3.14 and r is the radius of the circle.
- 14. Example:Find the areaof each of the following circles.
- 15. Find the areaof each of these circles.
- 16. Find the areaof each of the shapes below.
- 17. Definition: An annulus(plural annuli) is the shape formed between two circles with a common center (called concentric circles).
- 18. Find the areaof the annulus for the following sets of concentric circles.
- 19. Find the areaof the following shapes: