From the course: Preparing for the GMAT

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Circle proportions

Circle proportions

From the course: Preparing for the GMAT

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Circle proportions

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- [Instructor] So the GMAT sometimes likes to write questions that make you solve for a portion of a circle in terms of its arc length or a portion of its area, so in this video we'll talk about how to use a circle proportion formula to do that. So let's say we have a circle, and we know the radius is 4, so we would know that the total area, area is pi r squared, so if we square 4, we will get 16, so the area would be 16pi, and let's say we wanted to find the circumference, which is 2piR, be 2 time the radius, 2 times 4 is 8, so 8pi would be the circumference. So what if we had a wedge of this circle? What if I told you that that was 60 degrees and you were asked to find the area of that wedge? The formula that we're going to use for both of these situations in these videos is I'll write it down here, the whole over the whole equals the part over the part. We can always get this formula started with a circle proportion by filling in the whole degrees. So the whole degrees are always…

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