arc lengths and areas

13
Mr. Saucedo Milby High School Geometry

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Geometry HIgh School, lesson, Circles, Areas, Arc Lengths, Sectors, Introduction, Perimeter, Area, Volume Unit

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Page 1: Arc lengths and areas

Mr. SaucedoMilby High School

Geometry

Page 2: Arc lengths and areas

Objective:To find partial areas and circumferences of circles.

Page 3: Arc lengths and areas

What you should know…Find the

Circumference and the Area of a circle with diameter 10.

Page 4: Arc lengths and areas

WHAT IS?ARC LENGTH

An arc length is a fraction of the circumference.

Page 5: Arc lengths and areas

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?

Page 6: Arc lengths and areas

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

Page 7: Arc lengths and areas

GUIDED EXAMPLE 1Find the length of the arc:

Page 8: Arc lengths and areas

Independent exampleFind the length of the arc AB.

Page 9: Arc lengths and areas

SECTORSWhat is a sector?

Page 10: Arc lengths and areas

AREA OF A SECTORFORMULA:

AREA OF SECTOR = CENTRAL ANGLEAREA OF CIRCLE 360

AREA OF SECTOR = CENTRAL ANGLE пr2 360

Page 11: Arc lengths and areas

GUIDED EXAMPLE 2Find the area of the blue section

Page 12: Arc lengths and areas

INDEPENDENT EXAMPLEFind the area of the shaded region.

Page 13: Arc lengths and areas

HOMEWORKWORKBOOK (BLUE BOOK)

Pages: