TODAY IN GEOMETRY…

Review: Arc Length

Learning Target : 11.5 You will find area of circles and sectors

Independent practice

CIRCUMFERENCE OF A CIRCLE: The distance around a circle is found from the formula

𝑪=𝝅𝒅

We also know that:𝑑

𝑟 𝑟

𝑪=𝟐𝝅𝒓

ARC LENGTH: Part of the circumference

𝑃𝑟

𝑟𝐴

𝐵

𝑨𝒓𝒄 𝑳𝒆𝒏𝒈𝒕𝒉𝒐𝒇 𝑨𝑩=𝒎𝑨𝑩𝟑𝟔𝟎°

∙𝟐𝝅 𝒓

𝑨𝒓𝒄 𝑳𝒆𝒏𝒈𝒕𝒉𝒐𝒇 𝑨𝑩𝟐𝝅 𝒓

=𝒎𝑨𝑩𝟑𝟔𝟎°OR

REVIEW:1. Length of 2. Circumference of

¿𝑪

REVIEW:3. Length of

AREA OF A CIRCLE: The area of a circle is times the square of the radius.𝑨𝒓𝒆𝒂=𝝅 𝒓𝟐

𝑃

𝑟Practice: Find the area of the circle if the radius is 18m.

Exact AnswerRounded Answer

PRACTICE: Find the indicated measure.

AREA OF A SECTOR: Part of the area of a circle.

𝑃𝑟

𝐴

𝐵

𝑨𝒓𝒆𝒂𝒐𝒇 𝑺𝒆𝒄𝒕𝒐𝒓 𝑨𝑷𝑩=𝒎𝑨𝑩𝟑𝟔𝟎°

∙𝝅 𝒓𝟐

𝑨𝒓𝒆𝒂𝒐𝒇 𝑺𝒆𝒄𝒕𝒐𝒓 𝑨𝑷𝑩𝝅𝒓𝟐 =

𝒎𝑨𝑩𝟑𝟔𝟎°OR

2. Area of red sector

1. Area of

PRACTICE: Use the diagram to find the indicated measure.1. Area of 2. Area of red sector3. Area of blue sector

3. Area of blue sector

1. Area of 2. Area of red sector3. Area of blue sector

PRACTICE:

360 °85 °

∙ ∙360 °85 °

1. Area of a semicircle:2. Area of a triangle:3. Total area of the figure:

HOMEWORK #3:

Pg. 758: 7-9, 11-16, 27-29

If finished, work on other assignments:

HW #1: Pg. 723: 3-8, 16-18, 22-24 Pg. 733: 3-5, 10-12, 19-21HW #2: Pg. 749: 3-7, 11-13, 15-23