I learned about the sum of central angles. The sum of central angles is the sum of the measures of the central angles of a circle with no interior points in common is 360. An example is the measure of angle one plus the measure of angle two plus the measure of angle three equals 360. Also I learned about minor arcs, major arcs, and semicircles. A minor arc is the shortest arc connecting two endpoints on a circle. The measure of it is less than 180 and equal to the measure of its related central angle. A major arc is the longest arc connecting two endpoints on a circle. The measure of a major arc is greater than 180 and equal to 180 minus the measure of the minor arc with the same endpoints. A semicircle is an arc with endpoints that lie on a diameter. The measure of a semicircle always equals 180. You can use the sum of central angles, minor arcs, major arcs, and semicircles to find measures of central angles and the value of different angles. Also, I learned about the arc addition postulate. The arc addition postulate is when two arcs added together give you the measure of the two combining arcs. For example the measure of arc ABC equals the measure of arc AB plus the measure of arc BC. You can use this to find the measures of arcs. I also learned about an equation that can help you find the measures of arc lengths, finding the central angle/arc measures, and to find the circumference. The equation is arc AB equals (the measure of arc AB divided by 360) times 2πr. Lastly, I learned about how to find the perimeter of different objects.
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Alright amy, im going to help you out on how to find the circumfrence of that circle of yours. Well first of all we do know what the measure of the arch SR is, they give us 10.2, so what we have to do is plug that in our equation. we have 10.2= 45/360 x 2 x pie x radius. so first of all what we need to do is multiply both sides by 360, and then after that we need to divide 45 so we can get 2 x pie x r by itself. Then you plug that in your calculator and its 81.6. :)
ReplyDeleteNeither of these are real hard but dont feal bad i didnt get it at first either. All you have to do is take the circumfrence of each circle and ad them toghter. So you take 2 pie 6 to get the circumfernce for the on and 14 pie to get the other circle then add them toghter.
ReplyDeleteFor the next one you just find the circumfence then add 12 because there is two sides with 6 long so you add those. After you add them you just take 10 pie to get circumfrence and add them toghter.