[Video] Circles: Circumference & Arc Length

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In this series of videos, we will talk about geometric measures and will serve as a guide to areas and lengths related to circles.

The following videos talk about area and length of shapes related to circles:

Introduction to geometric measures: What is the circumference of a circle?

(Click the arrow to the right to see the Introduction video.)

Question 1: Circumference of circles

(Click the arrow to the right to see the first question.)

Using that $\pi \approx 3.14$ , what is the circumference of a circle with radius $3$ feet?
The circumference of a circle is about $\answer [tolerance=0.001]{18.84}$ feet.

Question 2: Not quite the circumference of circles

(Click the arrow to the right to see the first question.)

What is half of the circumference of a circle with radius $r$ ? Half of the circumference of a circle with radius $r$ is exactly $\answer [given]{\pi r}$ .

Arc Length: The length of the arc subtended by an angle

(Click the arrow to the right to see the Introduction video.)

Question 3: Arc Length

(Click the arrow to the right to see the third question.)

What is the arc length of an arc subtended by the angle $225^\circ$ for a circle with radius $3$ meters?
The arc length is exactly $\answer [given]{\frac {15\pi }{4}}$ .

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