MAP Recommended Practice
- Radius, diameter, circumference & π
- Labeling parts of a circle
- Radius, diameter, & circumference
- Radius and diameter
- Radius & diameter from circumference
- Relating circumference and area
- Circumference of a circle
- Area of a circle
- Area of a circle
- Partial circle area and arc length
- Circumference of parts of circles
- Area of parts of circles
- Circumference review
- Area of circles review
Radius, diameter, center, and circumference--all are parts of a circle. Let's go through each and understand how they are defined. Created by Sal Khan and Monterey Institute for Technology and Education.
Want to join the conversation?
- What is the center?(1 vote)
- why is half of the diameter called the radius(18 votes)
- at1:34what dont undertsand bro(5 votes)
- The circumference of a circle is basically the distance around a circle. For example, if you had a park or other outdoor area that was shaped in a perfect circle, and you walked all the way around the edge of it, you would have walked along the circumference of the circle. Basically, you can think of the circumference as the perimeter of a circle.(6 votes)
- what does the 'd' stand for?(3 votes)
- why are people answering people questions after a couple of years(2 votes)
- I am confused why do we use pi in this equation(2 votes)
- how do you find the diameter, radius, and the circumference of a circle(4 votes)
- The circumference of a circle is equal to pi times the diameter. The diameter is two times the radius, so the equation for the .circumference of a circle using the radius is two times pi times the radius.
Solve the equation for the diameter of the circle, d= C/π. In this example, "d = 12 / 3.14." or "The diameter is equal to twelve divided by 3.14." Divide the circumference by pi to get the answer. In this case, the diameter would be 3.82 inches.(1 vote)
- Is RADII singular form of RADIUS(3 votes)
- Are there other types of lines with specific names (like diameter and radius) other than a radius and diameter? Are there any with specific names that do not go through the center?(3 votes)
- If there was a line across a circle that didn't go through the center, we wouldn't need to give it a name or measure it, because it wouldn't give us any useful information regarding the circle.
For instance, if the line just went across a small part near the edge of the circle, we could measure it, but we wouldn't be able to do anything with the information-- i.e., find out the area of the circle.
We can only use lines that go through or come from the center of the circle to get information about the circle. Therefor, other measures are irrelevant.
Hope this helped! :)(1 vote)
Draw a circle and label the radius, diameter, center, and the circumference. Let me draw a circle. And it won't be that well drawn of a circle, but I think you get the idea. So that is my circle. I'm going to label the center over here. I'll do the center. I'll call it c. So that is my center. And I'll draw an arrow there. That is the center of the circle. And actually, the circle itself is the set of all points that are a fixed distance away from that center. And that fixed distance away that they're all from that center, that is the radius. So let me draw the radius. So this distance right over here is the radius. That is the radius. And that's going to be the same as this distance, which is the same as that distance. I can draw multiple radii. All of these are radii, the distance between the center and any point on the circle. Now, a diameter just goes straight across the circle, going through the center. From one side of the circle to the other side, I'm going through the center. It's essentially two radii put together. So for example, this would be a diameter. You have one radii, than another radii, all one line, going from one side of the circle to the other, going through the center. So that is a diameter. And I could have drawn it other ways. I could've drawn it like this. That would be another diameter. But they're going to have the exact same length. And finally, we have to think about the circumference. And the circumference is really just how far you have to go to go around the circle. Or if you put a string on this circle, how long will that string have to be? So what I'm tracing out in blue right now, the length of what I'm tracing out, is the circumference. So right over here, that is the circumference. And we're done.