Circles. 2 Circle: Plane figure Not a polygon Not made up of line segments.
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Transcript of Circles. 2 Circle: Plane figure Not a polygon Not made up of line segments.
Circles
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Circle:
• Plane figure• Not a polygon• Not made up of line segments
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Diameter:
• Longest chord, line, in a circle
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Radius
• Line segment with one endpoint at the center of the circle and the other endpoint on the circle.
• Half of the Diameter
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Area:
•A = r
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Find the area
77 cm
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Find the area
12 m
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Find the area
24 cm
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Find the area
• 56 ft
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Circumference:
• Distance around a circle• C = d• C = 2 r
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Find the circumference
77 cm
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Find the circumference
12 m
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Find the circumference
24 cm
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Find the circumference
• 56 ft
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All About Words
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Word Problems
• A circular shield has a diameter of 20 inches. Find the area of the steel needed to cover one side of the shield.
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Word Problems
• A pizza recipe calls for the dough to be rolled out to form a circle with a diameter of 18 inches. Find the area of the dough when it is rolled out.
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Word Problems
• The diameter of a circle that a shot-putter stands in is 7 feet. What is the area of the circle?
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Word Problems
• Meteor Crater in central Arizona was formed when an asteroid struck Earth between 20,000 and 50,000 years ago. The circular crater has a diameter of 1.2 kilometers. Find the area of the crater to the nearest hundredth.
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Word Problems
• An architect is making a plan for a new circular theater. The diameter of the theater is 32 meters. What is the circumference?
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Word Problems
• A builder is putting in a circular window. What is the circumference if the diameter is 4 feet?
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Word Problems
• A builder is putting in a circular window. What is the circumference if the radius is 2 feet?
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Word Problems
• A gardener is digging a circular pond. If the diameter of the pond is 5 yards. What is the circumference?
24
Word Problems
• The first Hula Hoop was introduced in 1958. What is the circumference of a Hula Hoop with a 3 foot diameter?
25
Word Problems
• The circumference of a circle is 24 meters. Find the diameter.
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Word Problems
• Stan needs a new bicycle tire. His tire has a circumference of about 113.04 inches. What is the diameter of the tire?
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Word Problems
• Billy Bob needs a new Hula Hoop. His Hula Hoop has a circumference of about 42.39 feet. What is the diameter of the Hula Hoop?
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Word Problems
• The circumference of a circle is 4
What is the area? Leave your answer in terms of pi.