Since the two radii must have the same length $(OA=OB)$, then $∠OAB=∠OBA$. We know that in triangles, if two sides are equal, then the angles opposite of those sides must be equal. We need their lengths! These radii are also part of $△AOB$, which is nice since we know that the perimeter of a triangle is the sum of its three sides. In Circle $O$, we can see two radii drawn: $OA$ and $OB$.
![perimeter of a circle perimeter of a circle](https://www.geogebra.org/resource/Fu8ku53x/oX0odRrk3e0ab4LZ/material-Fu8ku53x-thumb@l.png)
Okay, so if we can find the radius of the circle, then we could definitely calculate its circumference. Let’s think of what math equation we have for the circumference of a circle. We want to compare the circumference of circle $O$ to the value $12$. Let’s start with a top-down approach, where we will begin with what we’re looking for and work down to the details of what we’re given in this question.
![perimeter of a circle perimeter of a circle](http://selfpacedgeometry.weebly.com/uploads/1/2/8/6/12864445/295417_orig.png)
We are given the perimeter of $△AOB$ and we want to find the circumference of circle $O$, but it’s hard to see immediately how they’re connected. We want to compare the circumference of the circle to the value $12$.We know the perimeter of the triangle is $18$.One of the triangle’s angles $(∠AOB)$ is $60$ degrees.Two of the triangle’s sides $(OA \and OB)$ are radii of the circle.We have a triangle drawn inside a circle.Let’s carefully read through the question and make a list of the things that we know. So this question likely tests what we’ve learned about Triangles and Circles from geometry. We see that we have a triangle inside of a circle. Pay attention to any words that sound math-specific and anything special about what the numbers look like, and mark them on your paper. Let’s search the problem for clues as to what it will be testing, as this will help shift our minds to think about what type of math knowledge we’ll use to solve this question. Those Circles questions can be kind of tricky, but never fear, PrepScholar has got your back! Survey the Question Buuuut then you had some questions about the quant section-specifically question 1 of the first Quantitative section on Practice Test 1. So, you were trying to be a good test taker and practice for the GRE with PowerPrep online. The relationship cannot be determined from the information given.Or use the Facebook Comments form at the bottom of the page.$O$ is the center of the circle, and the perimeter of $△AOB$ is $6$. We would be grateful for any feedback on our quizzes, please let us know using our Contact Us link, We also collect the results from the quizzes which we use to help us to develop our resources and give us insight into future resources to create.įor more information on the information we collect, please take a look at our Privacy Policy We do not collect any personal data from our quizzes, except in the 'First Name' and 'Group/Class' fields which are both optional and only used for teachers to identify students within their educational setting.
Perimeter of a circle pdf#
You can print a copy of your results from this page, either as a pdf or as a paper copy.įor incorrect responses, we have added some helpful learning points to explain which answer was correct and why. This will take you to a new webpage where your results will be shown. Our quizzes have been created using Google Forms.Īt the end of the quiz, you will get the chance to see your results by clicking 'See Score'. If we calculate this to 1 decimal place, the answer is 75.4 m. So the circumference of this circle is π d = π x 24 or 24 π
![perimeter of a circle perimeter of a circle](https://cdn.vdocuments.mx/img/1200x630/reader016/image/20181124/56812cfb550346895d91ce18.png)
The radius of the circle is 12m, so the diameter is double this which is 24 m. Perimeter of a Circle Example 3įind the circumference of the circle below and give your answer to 1 decimal place. If we calculate this to the nearest cm, the answer is 22 inches. So the circumference of this circle is π d = π x 7 or 7 π inches. Perimeter of a Circle Example 2įind the circumference of the circle below to the nearest inch. So the circumference of this circle is π d = π x 5 or 5 π cm To find the circumference of a circle, we need to multiply the diameter by pi (π) Perimeter of a Circle Example 1įind the circumference of the circle below to 1 decimal place. Pi always has the same value which is 3.141592. Pi is a special mathematical number which is used to help calculate areas and perimeters of circles.
![perimeter of a circle perimeter of a circle](http://4.bp.blogspot.com/-_3g6F076Cy8/TgKlceonX3I/AAAAAAAAAB0/j4ydDUQ4JQ8/s1600/Screen+shot+2011-06-22+at+1.35.45+PM.png)
To find the perimeter of a circle, follow these simple steps: The perimeter of a circle is called the circumference.