TODAY IN GEOMETRY… Warm up: Writing equations of a circle Learning Target : 11.4 You will find...

TODAY IN GEOMETRY…

Warm up: Writing equations of a circle

Learning Target : 11.4 You will find the arc length and circumferences of circles

Independent practice

WARM UP:1. Write the standard 2. Graph the equation: equation of the circle.

(1 ,0)

3

Center: Radius: ¿ 4

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

PRACTICE: Find the indicated measure. Round answers to the nearest tenth.

1. Circumference of a circle 2. Radius of a circle with with radius 9 centimeters. circumference 26 meters.

PRACTICE: Find the indicated measure.

a. Find the circumference of a circle with diameter 5 inches. Find the diameter of a circle with circumference 17 feet.

b. A car tire has a diameter of 28 inches. How many revolutions does the tire make while traveling 500 feet?

ARC LENGTH: Part of the circumference

𝑨𝒓𝒄 𝑳𝒆𝒏𝒈𝒕𝒉𝒐𝒇 𝑨𝑩=𝒎𝑨𝑩𝟑𝟔𝟎°

∙𝟐𝝅 𝒓

𝑃

𝑟

𝑟𝐴

𝐵

Use equation for arc length

Substitute known values

Solve

EXAMPLE: Find the length of the red arc.



Solve

PRACTICE: Find the length of the red arc.



Solve

PRACTICE: Find the length of .



Solve

EXAMPLE: Find the circumference of .

Equation of circumference



Solve

PRACTICE: Find the circumference of .

Equation of circumference


Substitute known values Divide

Solve

PRACTICE: Find the circumference .


Substitute known values Divide

Solve

PRACTICE: Find the radius .

HOMEWORK #8:

Pg. 749: 3-7, 11-13, 15-23

If finished, work on other assignments:

HW #1: Pg. 655: 3-20, 24-26, 30HW #2: Pg. 661: 3-14, 17, 23HW #3: Pg. 667: 3-15HW #4: Pg. 676: 3-16 Pg. 679: 40-46HW #5: Pg. 683: 3-13HW #6: Pg. 692: 3, 4, 6, 9-14HW #7: Pg. 702: 3-25

TODAY IN GEOMETRY… Warm up: Writing equations of a circle Learning Target : 11.4 You will find...

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