Arc Lengths of a Circle

Arc Length

By Steven Giesting

​Recall from earlier classes that the distance around a circle is called the circumference.

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We can calculate the circumference in 1 of 2 ways.

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​Example 1: Find the circumference

Multiple Choice

What is the circumference of the circle shown?

• $$5\pi$$  

• $$10\pi$$  

• $$25\pi$$  

• $$50\pi$$  

​Today, we want to learn how to determine the length of an arc. Think about it like finding the distance we walk if we don't go all the way around the circle.

Multiple Choice

Find the length of arc PQ

• $$3\pi$$  

• $$\frac{27\pi}{2}$$  

• $$\frac{3\pi}{2}$$  

• $$6\pi$$  

Multiple Choice

What is the length of arc PQ

• $$3\pi$$  

• $$6\pi$$  

• $$9\pi$$  

• $$18\pi$$