Arc lengths and areas
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Transcript of Arc lengths and areas
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Mr. SaucedoMilby High School
Geometry
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Objective:To find partial areas and circumferences of circles.
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What you should know…Find the
Circumference and the Area of a circle with diameter 10.
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WHAT IS?ARC LENGTH
An arc length is a fraction of the circumference.
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The concept…Can you find the arc length of thisSemicircle?
What would the arc length be if we just wanted to use a quarter of the circle?
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HOW DO WE FIND ARC LENGHTS?
With the following proportion:
Part of a circumference = Portion of degrees
Whole Circumference Whole: Degrees in a circle
Arc length = Central Angle пD 360
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GUIDED EXAMPLE 1Find the length of the arc:
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Independent exampleFind the length of the arc AB.
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SECTORSWhat is a sector?
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AREA OF A SECTORFORMULA:
AREA OF SECTOR = CENTRAL ANGLEAREA OF CIRCLE 360
AREA OF SECTOR = CENTRAL ANGLE пr2 360
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GUIDED EXAMPLE 2Find the area of the blue section
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INDEPENDENT EXAMPLEFind the area of the shaded region.
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HOMEWORKWORKBOOK (BLUE BOOK)
Pages: