In section 11.3 you will be find the area of a sector, or the area of a section of a circle, like a piece of pie. You will also be finding the arc length on a circle. To find the area of a sector in a circle or the arc length of a circle you will be setting up proportions.
As you read through the section below fill in the blanks on the handout that has been provided for you.
Area of Sector:
As you read through the section below fill in the blanks on the handout that has been provided for you.
Area of Sector:
To find the area of a sector you will set up a proportion following the pattern part/whole = part/whole. On one side of the proportion the part will be the angle of the sector and the whole will be 360 degrees, because the total angle measure of every circle is 360 degrees. On the other side of the proportion will be the unknown area of the sector we are looking for and the total area of the circle. Once you have the proportion filled in you cross multiply and divide. Take a look at the examples on the following site to help illustrate this, don't worry about watching the videos, just take notes on the examples.
http://www.onlinemathlearning.com/area-sector.html
Arc Length:
Earlier in this chapter we discussed finding the angle measure of an arc on a circle, now you will be finding the length of an arc on a circle. This means it will be a distance that can be measured in units such as inches or centimeters, not degrees. To find the arc length you need to set up a proportion. You will start to set it up similar to the explanation above for finding area of a sector. On one side of the proportion you have the angle measure of the arc over 360 (the total angle measure of any circle). Next, this equals the unknown arc length (x), over the total circumference of the circle (use the equation for circumference of a circle). Cross multiply the two ratios and divide to find the arc length. Use this site to help describe this explanation, don't worry about watching the videos.
http://www.onlinemathlearning.com/arc-circle.html
http://www.onlinemathlearning.com/area-sector.html
Arc Length:
Earlier in this chapter we discussed finding the angle measure of an arc on a circle, now you will be finding the length of an arc on a circle. This means it will be a distance that can be measured in units such as inches or centimeters, not degrees. To find the arc length you need to set up a proportion. You will start to set it up similar to the explanation above for finding area of a sector. On one side of the proportion you have the angle measure of the arc over 360 (the total angle measure of any circle). Next, this equals the unknown arc length (x), over the total circumference of the circle (use the equation for circumference of a circle). Cross multiply the two ratios and divide to find the arc length. Use this site to help describe this explanation, don't worry about watching the videos.http://www.onlinemathlearning.com/arc-circle.html
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