Arc length measurement

Sal finds the length of an arc using the radius and the radian measure of the angle subtended by the arc. However, the arc LENGTH is different. The arc measure is equal to the angle value.

This information should be given, or you should be able to measure it. Make sure you are working with degrees, and not radians, when using this formula.

How do you find the Length of the Arc?

What if you want the Arc Length to drive your sketch?

The length of an arc is simply the length of its portion of the circumference. Calculating the lengths of arcs and areas of sectors. The first step is to find the angle made by the arc or sector at the centre of the circle. Once you have done that, calculating the length of the arc or area of the sector is possible.

Remember Circumference = πd or 2πr. An arc is not always 2r, although this one happened to be equal to twice the length of the radius. The cool thing about radians as an angle measurement is that they are exactly related to the length of the radius so you can use proportions to . So this is the center of the circle. Watch Sal solve an example where he finds the central angle given arc length.

The denominator multiplied by the circumference equals 3pi, so any angle would match the arc length given. Solve problems related to radians and arc length like finding an arc length given the central angle and radius. At the prompt, enter L ( Arc Length ). Repeat steps to continue dimensioning or press Enter to end dimensioning. Click to place the dimension line. Historically, many methods were used for specific curves.

Time-saving video on how to define arc length , compare it to arc measure , and calculate arc length. Example problems calculate arc length and find missing arc measures. But it can, at least, be enjoyable.

Notice that cuts off or determines an arc that has length s. So the radian measure of is given by: Arc length , s, and radius, r, must be in the same units.