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 * Aim: How do we find the length of an arc?

In this lesson you will learn the formula to determine the arc length of a circle and prctice finding arc length or radius.


 * Before you watch the video, here are some questions you need to copy into your notebooks. You will answer these as you watch the video:

1. What is the equation for arc length? 2. In what format do we write the angle? 3. What is the formula to find theta (the angle)? 4. Do you need to memorize both formulas? Justify your answer. 5. What is another way to convert from degree to radian measure?

[|Video #1]

This video also talks about area of a sector. This is not a required topic for the Regents but it does not hurt to learn something extra

[|Video 2]


 * **Classwork**: Answer the following questions in your notebook:

1. The radius of a circle is 4 cm. A central angle of the circle intercepts an arc of 12 cm. What is the radian measure of the angle? Is the angle acute, obtuse, or larger that a straight angle?

2. The radius of a circle is 8 inches. What is the length of the intercepted arc by a central angle of a circle if the measure of the angle is 2.5 radians?


 * **Homework:** Complete odd exercises


 * [|8.3_Arc_length.JPG]**


 * **Answers**

[|A-8.3_Arc_length.JPG]


 * **Journal entry**:

How do degree measure and arc length differ?