{"appState":{"pageLoadApiCallsStatus":true},"articleState":{"article":{"headers":{"creationTime":"2016-07-05T20:32:17+00:00","modifiedTime":"2016-08-24T13:45:38+00:00","timestamp":"2022-09-14T18:15:23+00:00"},"data":{"breadcrumbs":[{"name":"Academics & The Arts","_links":{"self":"https://dummies-api.dummies.com/v2/categories/33662"},"slug":"academics-the-arts","categoryId":33662},{"name":"Study Skills & Test Prep","_links":{"self":"https://dummies-api.dummies.com/v2/categories/33772"},"slug":"study-skills-test-prep","categoryId":33772},{"name":"Armed Services","_links":{"self":"https://dummies-api.dummies.com/v2/categories/33776"},"slug":"armed-services","categoryId":33776}],"title":"ASVAB Preparation: Circles","strippedTitle":"asvab preparation: circles","slug":"asvab-preparation-circles","canonicalUrl":"","seo":{"metaDescription":"You will need to be familiar with some circle basics for the ASVAB. A circle is formed when the points of a closed line are all located an equal distance from i","noIndex":0,"noFollow":0},"content":"You will need to be familiar with some circle basics for the ASVAB. A circle is formed when the points of a closed line are all located an equal distance from its center. A circle always has 360 ͦ. Here are some key circle terms:\r\n<ul>\r\n\t<li><strong>Circumference (C):</strong> The closed line of a circle — that is, the distance around the circle — is called its circumference.</li>\r\n\t<li><strong>Radius (r)</strong>: The radius of a circle is the measurement from the center of the circle to any point on the circumference of the circle.</li>\r\n\t<li><strong>Diameter (d)</strong>: The diameter of the circle is measured as a line passing through the center of the circle, from a point on one side of the circle all the way to a point on the other side of the circle.</li>\r\n</ul>\r\n<p class=\"article-tips remember\">The diameter of a circle is always twice as long as the radius of a circle: <em>a=2r</em>.</p>\r\n\r\n\r\n[caption id=\"attachment_221193\" align=\"aligncenter\" width=\"127\"]<a href=\"https://www.dummies.com/wp-content/uploads/Parts-of-a-Circle.jpg\"><img class=\"wp-image-221193 size-full\" src=\"https://www.dummies.com/wp-content/uploads/Parts-of-a-Circle.jpg\" alt=\"Parts of a Circle\" width=\"127\" height=\"128\" /></a> Parts of a circle.[/caption]\r\n<h2 id=\"tab1\" >Navigating the circumference</h2>\r\nTo measure the circumference of a circle, use the number pi (π). Although π is a lengthy number, it’s generally rounded to 3.14 or 22/7. If you round π so you can solve a problem, the equal sign isn’t used because the answer isn’t equal to the actual length. The approximation symbol (≈) is used.\r\n<p class=\"article-tips remember\">The formula for circumference is circumference = π × diameter, or C = πd. Because the radius of a circle is half its diameter, you can also use the radius to determine the circumference of a circle. Here’s the formula: C = 2πr.</p>\r\nSuppose you know that the pie you just baked has a diameter of 9 inches. You can determine its circumference by using the circumference formula:\r\n\r\n<em>C</em> = π<em>d</em>\r\n<em>C</em> ≈ 3.14 × 9\r\n<em>C</em> ≈ 28.26 inches\r\n<h2 id=\"tab2\" >Mapping out the area</h2>\r\nDetermining the area of a circle also requires the use of π. <em>Area</em> = π<em>x</em> the square of the circle’s radius, or <em>A</em> = π<em>r</em><sup>2</sup>.\r\n\r\nTo determine the area of a 9-inch-diameter pie, multiply π by the square of 4.5. Why 4.5 and not 9? Remember, the radius is always half the diameter, and the diameter is 9 inches.\r\n\r\n<em>A</em> = <em>xr</em><sup>2\r\n</sup><em>A</em> = 3.14 × 4.5<sup>2\r\n</sup><em>A</em> = 3.14 × (4.5 × 4.5)\r\n<em>A</em> = 3.14 × 20.25\r\n<em>A</em> = 63.585 inches","description":"You will need to be familiar with some circle basics for the ASVAB. A circle is formed when the points of a closed line are all located an equal distance from its center. A circle always has 360 ͦ. Here are some key circle terms:\r\n<ul>\r\n\t<li><strong>Circumference (C):</strong> The closed line of a circle — that is, the distance around the circle — is called its circumference.</li>\r\n\t<li><strong>Radius (r)</strong>: The radius of a circle is the measurement from the center of the circle to any point on the circumference of the circle.</li>\r\n\t<li><strong>Diameter (d)</strong>: The diameter of the circle is measured as a line passing through the center of the circle, from a point on one side of the circle all the way to a point on the other side of the circle.</li>\r\n</ul>\r\n<p class=\"article-tips remember\">The diameter of a circle is always twice as long as the radius of a circle: <em>a=2r</em>.</p>\r\n\r\n\r\n[caption id=\"attachment_221193\" align=\"aligncenter\" width=\"127\"]<a href=\"https://www.dummies.com/wp-content/uploads/Parts-of-a-Circle.jpg\"><img class=\"wp-image-221193 size-full\" src=\"https://www.dummies.com/wp-content/uploads/Parts-of-a-Circle.jpg\" alt=\"Parts of a Circle\" width=\"127\" height=\"128\" /></a> Parts of a circle.[/caption]\r\n<h2 id=\"tab1\" >Navigating the circumference</h2>\r\nTo measure the circumference of a circle, use the number pi (π). Although π is a lengthy number, it’s generally rounded to 3.14 or 22/7. If you round π so you can solve a problem, the equal sign isn’t used because the answer isn’t equal to the actual length. The approximation symbol (≈) is used.\r\n<p class=\"article-tips remember\">The formula for circumference is circumference = π × diameter, or C = πd. Because the radius of a circle is half its diameter, you can also use the radius to determine the circumference of a circle. Here’s the formula: C = 2πr.</p>\r\nSuppose you know that the pie you just baked has a diameter of 9 inches. You can determine its circumference by using the circumference formula:\r\n\r\n<em>C</em> = π<em>d</em>\r\n<em>C</em> ≈ 3.14 × 9\r\n<em>C</em> ≈ 28.26 inches\r\n<h2 id=\"tab2\" >Mapping out the area</h2>\r\nDetermining the area of a circle also requires the use of π. <em>Area</em> = π<em>x</em> the square of the circle’s radius, or <em>A</em> = π<em>r</em><sup>2</sup>.\r\n\r\nTo determine the area of a 9-inch-diameter pie, multiply π by the square of 4.5. Why 4.5 and not 9? Remember, the radius is always half the diameter, and the diameter is 9 inches.\r\n\r\n<em>A</em> = <em>xr</em><sup>2\r\n</sup><em>A</em> = 3.14 × 4.5<sup>2\r\n</sup><em>A</em> = 3.14 × (4.5 × 4.5)\r\n<em>A</em> = 3.14 × 20.25\r\n<em>A</em> = 63.585 inches","blurb":"","authors":[{"authorId":9112,"name":"Rod Powers","slug":"rod-powers","description":" <p><b>Angie Papple Johnston</b> joined the U.S. Army in 2006 as a CBRN specialist. Currently, she's the CBRN noncommissioned officer-in-charge of an aviation battalion in Washington, D.C. <b>Rod Powers</b> served more than 20 years in the U.S. Air Force and retired as a first sergeant. ","hasArticle":false,"_links":{"self":"https://dummies-api.dummies.com/v2/authors/9112"}}],"primaryCategoryTaxonomy":{"categoryId":33776,"title":"Armed Services","slug":"armed-services","_links":{"self":"https://dummies-api.dummies.com/v2/categories/33776"}},"secondaryCategoryTaxonomy":{"categoryId":0,"title":null,"slug":null,"_links":null},"tertiaryCategoryTaxonomy":{"categoryId":0,"title":null,"slug":null,"_links":null},"trendingArticles":null,"inThisArticle":[{"label":"Navigating the circumference","target":"#tab1"},{"label":"Mapping out the area","target":"#tab2"}],"relatedArticles":{"fromBook":[],"fromCategory":[{"articleId":283798,"title":"Mastering the Science of Movement Training for the ACFT","slug":"mastering-the-science-of-movement-training-for-the-acft","categoryList":["academics-the-arts","study-skills-test-prep","armed-services"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/283798"}},{"articleId":283793,"title":"ACFT Event: Two-Mile Run","slug":"acft-event-two-mile-run","categoryList":["academics-the-arts","study-skills-test-prep","armed-services"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/283793"}},{"articleId":283786,"title":"ACFT Event: Leg Tuck","slug":"acft-event-leg-tuck","categoryList":["academics-the-arts","study-skills-test-prep","armed-services"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/283786"}},{"articleId":283778,"title":"ACFT Event: Sprint-Drag-Carry","slug":"acft-event-sprint-drag-carry","categoryList":["academics-the-arts","study-skills-test-prep","armed-services"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/283778"}},{"articleId":283759,"title":"ACFT Event: 3 Repetition Maximum Deadlift","slug":"acft-event-3-repetition-maximum-deadlift","categoryList":["academics-the-arts","study-skills-test-prep","armed-services"],"_links":{"self":"https://dummies-api.dummies.com/v2/articles/283759"}}]},"hasRelatedBookFromSearch":true,"relatedBook":{"bookId":281914,"slug":"1001-asvab-practice-questions-for-dummies-free-online-practice","isbn":"9781394174249","categoryList":["academics-the-arts","study-skills-test-prep","armed-services"],"amazon":{"default":"https://www.amazon.com/gp/product/1394174241/ref=as_li_tl?ie=UTF8&tag=wiley01-20","ca":"https://www.amazon.ca/gp/product/1394174241/ref=as_li_tl?ie=UTF8&tag=wiley01-20","indigo_ca":"http://www.tkqlhce.com/click-9208661-13710633?url=https://www.chapters.indigo.ca/en-ca/books/product/1394174241-item.html&cjsku=978111945484","gb":"https://www.amazon.co.uk/gp/product/1394174241/ref=as_li_tl?ie=UTF8&tag=wiley01-20","de":"https://www.amazon.de/gp/product/1394174241/ref=as_li_tl?ie=UTF8&tag=wiley01-20"},"image":{"src":"https://www.dummies.com/covers/9781394174249.jpg","width":250,"height":350},"title":"ASVAB: 1001 Practice Questions For Dummies (+ Online Practice)","testBankPinActivationLink":"","bookOutOfPrint":true,"authorsInfo":"\n <p><p><b><b data-author-id=\"9112\">Rod Powers</b>,</b> a recognized expert in all U.S. military matters, is the author of <i>ASVAB For Dummies</i> and serves as a military guide for About.com. <p><b><b data-author-id=\"11018\">Angie Papple Johnston</b></b> joined the U.S. Army in 2006 as a Chemical, Biological, Radiological, and Nuclear Specialist. 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She also served as the Lead Cadre for the Texas Army National Guard’s Recruit Sustainment program.</p> ","hasArticle":false,"_links":{"self":"https://dummies-api.dummies.com/v2/authors/11018"}}],"_links":{"self":"https://dummies-api.dummies.com/v2/books/281914"}},"collections":[],"articleAds":{"footerAd":"<div class=\"du-ad-region row\" id=\"article_page_adhesion_ad\"><div class=\"du-ad-unit col-md-12\" data-slot-id=\"article_page_adhesion_ad\" data-refreshed=\"false\" \r\n data-target = \"[{"key":"cat","values":["academics-the-arts","study-skills-test-prep","armed-services"]},{"key":"isbn","values":[null]}]\" id=\"du-slot-63221a3bd94e6\"></div></div>","rightAd":"<div class=\"du-ad-region row\" id=\"article_page_right_ad\"><div class=\"du-ad-unit col-md-12\" data-slot-id=\"article_page_right_ad\" data-refreshed=\"false\" \r\n data-target = \"[{"key":"cat","values":["academics-the-arts","study-skills-test-prep","armed-services"]},{"key":"isbn","values":[null]}]\" 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ASVAB Preparation: Circles

By: Rod Powers and

Updated: 08-24-2016

ASVAB: 1001 Practice Questions For Dummies (+ Online Practice)

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You will need to be familiar with some circle basics for the ASVAB. A circle is formed when the points of a closed line are all located an equal distance from its center. A circle always has 360 ͦ. Here are some key circle terms:

Circumference (C): The closed line of a circle — that is, the distance around the circle — is called its circumference.
Radius (r): The radius of a circle is the measurement from the center of the circle to any point on the circumference of the circle.
Diameter (d): The diameter of the circle is measured as a line passing through the center of the circle, from a point on one side of the circle all the way to a point on the other side of the circle.

The diameter of a circle is always twice as long as the radius of a circle: a=2r.

Parts of a Circle

Parts of a circle.

Navigating the circumference

To measure the circumference of a circle, use the number pi (π). Although π is a lengthy number, it’s generally rounded to 3.14 or 22/7. If you round π so you can solve a problem, the equal sign isn’t used because the answer isn’t equal to the actual length. The approximation symbol (≈) is used.

The formula for circumference is circumference = π × diameter, or C = πd. Because the radius of a circle is half its diameter, you can also use the radius to determine the circumference of a circle. Here’s the formula: C = 2πr.

Suppose you know that the pie you just baked has a diameter of 9 inches. You can determine its circumference by using the circumference formula:

C = πd C ≈ 3.14 × 9 C ≈ 28.26 inches

Mapping out the area

Determining the area of a circle also requires the use of π. Area = πx the square of the circle’s radius, or A = πr².

To determine the area of a 9-inch-diameter pie, multiply π by the square of 4.5. Why 4.5 and not 9? Remember, the radius is always half the diameter, and the diameter is 9 inches.

A = xr²A = 3.14 × 4.5²A = 3.14 × (4.5 × 4.5) A = 3.14 × 20.25 A = 63.585 inches

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