Mr. Saucedo
Milby High School
Geometry
Objective:
To find partial areas and

circumferences of circles.
What you should know…
Find the

Circumference and the
Area of a circle with
diameter 10.
WHAT IS?
ARC LENGTH

An arc length is a fraction of the circumference.
The concept…
Can you find the arc length of this
Semicircle?

What would the arc length be if we just wanted to use a
quar...
HOW DO WE FIND ARC LENGHTS?
With the following proportion:

Part of a circumference
Whole Circumference
circle

Arc lengt...
GUIDED EXAMPLE 1
Find the length of the arc:
Independent example
Find the length of the arc AB.
SECTORS
What is a sector?
AREA OF A SECTOR
FORMULA:

AREA OF SECTOR
AREA OF CIRCLE

=

CENTRAL ANGLE
360

AREA OF SECTOR = CENTRAL ANGLE
пr2
360
GUIDED EXAMPLE 2
Find the area of the blue section
INDEPENDENT EXAMPLE
Find the area of the shaded region.
HOMEWORK
WORKBOOK (BLUE BOOK)

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Arc lengths and areas

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

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Arc lengths and areas

  1. 1. Mr. Saucedo Milby High School Geometry
  2. 2. Objective: To find partial areas and circumferences of circles.
  3. 3. What you should know… Find the Circumference and the Area of a circle with diameter 10.
  4. 4. WHAT IS? ARC LENGTH An arc length is a fraction of the circumference.
  5. 5. The concept… Can you find the arc length of this Semicircle? What would the arc length be if we just wanted to use a quarter of the circle?
  6. 6. HOW DO WE FIND ARC LENGHTS? With the following proportion: Part of a circumference Whole Circumference circle Arc length пD = Portion of degrees Whole: Degrees in a = Central Angle 360
  7. 7. GUIDED EXAMPLE 1 Find the length of the arc:
  8. 8. Independent example Find the length of the arc AB.
  9. 9. SECTORS What is a sector?
  10. 10. AREA OF A SECTOR FORMULA: AREA OF SECTOR AREA OF CIRCLE = CENTRAL ANGLE 360 AREA OF SECTOR = CENTRAL ANGLE пr2 360
  11. 11. GUIDED EXAMPLE 2 Find the area of the blue section
  12. 12. INDEPENDENT EXAMPLE Find the area of the shaded region.
  13. 13. HOMEWORK WORKBOOK (BLUE BOOK) Pages:

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