{"id":7439,"date":"2016-07-06T16:39:33","date_gmt":"2016-07-06T23:39:33","guid":{"rendered":"https:\/\/magoosh.com\/act\/?p=7439"},"modified":"2016-07-01T16:40:41","modified_gmt":"2016-07-01T23:40:41","slug":"act-math-how-to-solve-circle-problems","status":"publish","type":"post","link":"https:\/\/magoosh.com\/act\/act-math-how-to-solve-circle-problems\/","title":{"rendered":"ACT Math: How to Solve Circle Problems"},"content":{"rendered":"<p>Solving problems that have to deal with circles may look intimidating at first, so I&#8217;ll break down what to look out for when dealing with circles on <a href=\"https:\/\/magoosh.com\/act\/15-key-concepts-act-math-review\/\">ACT Math<\/a>. After that, we&#8217;ll go right into the skills and definitions needed for the test.<\/p>\n<p>The formulas themselves are not too difficult to remember. What might trip you up, however, are the vast amount of key terms you are expected to know.<\/p>\n<p>Lastly, since ACT test makers have a tendency to combine circles, triangles, and other possibe shapes together in one problem, you&#8217;ll need to utilize skills from all parts of your geometry toolkit to handle them.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-7440 size-large\" src=\"https:\/\/s3.amazonaws.com\/magoosh-company-site\/wp-content\/uploads\/hs\/files\/2016\/06\/29012844\/2000px-Pi_eq_C_over_d.svg_-600x600.png\" alt=\"circles on act math -magoosh\" width=\"600\" height=\"600\" \/><\/p>\n<h2>ACT Math: Definition of a Circle<\/h2>\n<p>A circle is a set of all the points that are equidistant from a point (the center of the circle). You probably already know what a circle looks like, but it&#8217;s important to know the formal definition so that you can confidently handle any conceptual problems that come up.<\/p>\n<h2>ACT Math: Glossary of Circle Terms<\/h2>\n<p><strong>Radius<\/strong><\/p>\n<p>A line drawn from the center of a circle out to the edge of the circle.<\/p>\n<p>Formula: r<\/p>\n<p><strong>Diameter<\/strong><\/p>\n<p>A line drawn from one edge of a circle out to the other side of the circle. It goes through the center of the circle, cutting it in half.<\/p>\n<p>Formula: 2r<\/p>\n<p><strong>Circumference<\/strong><\/p>\n<p>The length of the perimeter of the circle.<\/p>\n<p>Formula: 2*(pi)*r<\/p>\n<p><strong>Area<\/strong><\/p>\n<p>The size of the enclosed region of a circle.<\/p>\n<p>Formula: (pi)r<sup>2<\/sup><\/p>\n<p><strong>Arc Length<\/strong><\/p>\n<p>The length of a particular fraction of the circumference of a circle.<\/p>\n<p>Formula: (x\/360)*circumference<\/p>\n<p>X equals the number of degrees of the arc&#8217;s central angle.<\/p>\n<p><strong>Minor Arc<\/strong><\/p>\n<p>The shorter distance along a circle between two points on the edge of the circle.<\/p>\n<p><strong>Major Arc<\/strong><\/p>\n<p>The longer distance along a circle between two points on the edge of the circle.<\/p>\n<p><strong>Sector<\/strong><\/p>\n<p>The area of a circle enclosed by an arc and two radii.<\/p>\n<p>Formula: (n\/360)*(Area)<\/p>\n<p>N is the degree measure of the central angle of the sector.<\/p>\n<p><strong>Concentric Circles<\/strong><\/p>\n<p>Circles that have the same center and are of a different size.<\/p>\n<p><strong>Semicircle<\/strong><\/p>\n<p>Half of a circle is called a semicircle.<\/p>\n<p><strong>Chord<\/strong><\/p>\n<p>A line that goes from one edge of the circle to the other side. Unlike the diameter, chords don&#8217;t necessarily have to go through the center.<\/p>\n<p>A diameter is a chord, but a chord is not necessarily a diameter.<\/p>\n<p><strong>Tangent<\/strong><\/p>\n<p>A line on the outside of the circle that touches the circle at only one point. The radius of the circle that touches that point forms a right angle with the tangent line.<\/p>\n<p><strong>Central Angle<\/strong><\/p>\n<p>The angle that is formed by two radii.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Math problems about circles may look intimidating at first, so this post breaks down what to look out for when dealing with circles on ACT Math.<\/p>\n","protected":false},"author":158,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[90],"tags":[],"ppma_author":[24918],"class_list":["post-7439","post","type-post","status-publish","format-standard","hentry","category-all"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v21.7 (Yoast SEO v21.7) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>ACT Math: How to Solve Circle Problems<\/title>\n<meta name=\"description\" content=\"Math problems about circles may 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