Post on 02-Jan-2016
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10-7 Areas of Circles and Sectors
ObjectiveTo find the areas of circles,
sectors, and segments of circles
Theorem 10-11 Area of a Circle
• The area of a circle is the product of π and the square of the radius.
Sector of a circle
The region bounded by 2 radii and their intercepted arc
Ex would be a slice of pizza Sectors are named by using one
endpoint of the arc, the center, and the other endpoint
Theorem 10-12 Area of a sector of a circle
The area of a sector of a circle is the product of the ratio (measure of arc/360) and the area of the circle.
𝑨𝒓𝒆𝒂=𝒎𝒆𝒂𝒔𝒖𝒓𝒆𝒐𝒇 𝒂𝒓𝒄
𝟑𝟔𝟎∙𝝅 𝒓𝟐
Ex. 3
Circle has a d = 20 cm. What is the area of a sector bounded by 208° arc? Round to the nearest tenth.
To find the area of a segment
• 1st draw in the radii to form a sector.• 2nd find the area of the sector• 3rd find the area of the triangle• 4th subtract (sector-triangle)