{"id":3289,"date":"2012-08-27T16:14:42","date_gmt":"2012-08-27T16:14:42","guid":{"rendered":"http:\/\/SchoolTutoring.com\/help\/?p=3289"},"modified":"2014-12-02T08:32:05","modified_gmt":"2014-12-02T08:32:05","slug":"linear-equations-point-of-intersection-of-lines","status":"publish","type":"post","link":"https:\/\/schooltutoring.com\/help\/linear-equations-point-of-intersection-of-lines\/","title":{"rendered":"Linear Equations: Point of Intersection of Lines"},"content":{"rendered":"<p>The point of intersection of two or more lines is a point which lies on all the given lies. It means the equations of all the given lines must be satisfied by the intersection point. This point of intersection of lines is called the \u201cpoint of concurrency\u201d.\u00a0 Finding this point of concurrency of two lines from given set of lines is used to determine whether the other lines are concurrent with these two lines.<\/p>\n<h4>Point of intersection of two lines:<\/h4>\n<p>Let two lines<strong> a<sub>1<\/sub>x+b<sub>1<\/sub>y+c<sub>1<\/sub> =0<\/strong> and <strong>a<sub>2<\/sub>x + b<sub>2<\/sub>y + c<sub>2<\/sub>=0<\/strong> represent two intersecting lines.<\/p>\n<p>Let the intersecting point of these two lines be<strong> (x<sub>1<\/sub>,y<sub>1<\/sub>).<\/strong><\/p>\n<p>Then it must lie on both the lines.<\/p>\n<p><strong>a<sub>1<\/sub>x<sub>1<\/sub>+b<sub>1<\/sub>y<sub>1<\/sub>+c<sub>1<\/sub>=0<\/strong><\/p>\n<p><strong>a<sub>2<\/sub>x<sub>1<\/sub>+b<sub>2<\/sub>y<sub>1<\/sub>+c<sub>2<\/sub>=0<\/strong><\/p>\n<p>Solving these two equation, we get<\/p>\n<p><strong>(x<sub>1<\/sub>,y<sub>1<\/sub>)=([b<sub>1<\/sub>c<sub>2<\/sub>-b<sub>2<\/sub>c<sub>1<\/sub>]\/[a<sub>1<\/sub>b<sub>2<\/sub>-a<sub>2<\/sub>b<sub>1<\/sub>], [c<sub>1<\/sub>a<sub>2<\/sub>-c<sub>2<\/sub>a<sub>1<\/sub>]\/[a<sub>1<\/sub>b<sub>2<\/sub>-a<sub>2<\/sub>b<sub>1<\/sub>])<\/strong><\/p>\n<p><strong>Example:<\/strong><\/p>\n<p>Find the point of intersection of lines<strong> 2x+3y-8=0<\/strong> and<strong> x-y +1=0.<\/strong><\/p>\n<p><strong>Solution:<\/strong><\/p>\n<p><strong>Here a<sub>1<\/sub>=2, b<sub>1<\/sub>=3, c<sub>1<\/sub>=-8 and a<sub>2<\/sub>=1, b<sub>2<\/sub>=-1, c<sub>2<\/sub>=1,<\/strong><\/p>\n<p>Pint of intersection <strong>(x,y) = ([b<sub>1<\/sub>c<sub>2<\/sub>-b<sub>2<\/sub>c<sub>1<\/sub>]\/[a<sub>1<\/sub>b<sub>2<\/sub>-a<sub>2<\/sub>b<sub>1<\/sub>], [c<sub>1<\/sub>a<sub>2<\/sub>-c<sub>2<\/sub>a<sub>1<\/sub>]\/[a<sub>1<\/sub>b<sub>2<\/sub>-a<sub>2<\/sub>b<sub>1<\/sub>])<\/strong><\/p>\n<p><strong>=([3-8]\/[-2-3], [-8-2]\/ [-2-3])=(-5\/-5, -10\/-5)=(1,2).<\/strong><\/p>\n<h4>Condition for point of concurrency of 3 lines:<\/h4>\n<p>Let the <strong>3<\/strong> lines <strong>a<sub>1<\/sub>x+b<sub>1<\/sub>y+c<sub>1<\/sub> =0, a<sub>2<\/sub>x + b<sub>2<\/sub>y + c<sub>2<\/sub>=0<\/strong> and <strong>a<sub>3<\/sub>x + b<sub>3<\/sub>y + c<sub>3<\/sub>=0<\/strong> be concurrent. Then the point of intersection of first two lines must lie on the third line.<\/p>\n<p>i.e. <strong>([b<sub>1<\/sub>c<sub>2<\/sub>-b<sub>2<\/sub>c<sub>1<\/sub>]\/[a<sub>1<\/sub>b<sub>2<\/sub>-a<sub>2<\/sub>b<sub>1<\/sub>], [c<sub>1<\/sub>a<sub>2<\/sub>-c<sub>2<\/sub>a<sub>1<\/sub>]\/[a<sub>1<\/sub>b<sub>2<\/sub>-a<sub>2<\/sub>b<sub>1<\/sub>])<\/strong> must line on the line <strong>a<sub>3<\/sub>x + b<sub>3<\/sub>y + c<sub>3<\/sub>=0.<\/strong><\/p>\n<p>So, <strong>a<sub>3<\/sub> [b<sub>1<\/sub>c<sub>2<\/sub>-b<sub>2<\/sub>c<sub>1<\/sub>]\/[a<sub>1<\/sub>b<sub>2<\/sub>-a<sub>2<\/sub>b<sub>1<\/sub>] \u00a0+ b<sub>3 <\/sub>[c<sub>1<\/sub>a<sub>2<\/sub>-c<sub>2<\/sub>a<sub>1<\/sub>]\/[a<sub>1<\/sub>b<sub>2<\/sub>-a<sub>2<\/sub>b<sub>1<\/sub>] \u00a0+ c<sub>3 <\/sub>= 0<\/strong><\/p>\n<p>Then we get<\/p>\n<p><strong>a<sub>3<\/sub> [b<sub>1<\/sub>c<sub>2<\/sub>-b<sub>2<\/sub>c<sub>1<\/sub>] + b<sub>3 <\/sub>[c<sub>1<\/sub>a<sub>2<\/sub>-c<sub>2<\/sub>a<sub>1<\/sub>] + c<sub>3 <\/sub>[a<sub>1<\/sub>b<sub>2<\/sub>-a<sub>2<\/sub>b<sub>1<\/sub>] = 0.<\/strong><\/p>\n<p><strong>Example:<\/strong><\/p>\n<p>Determine whether the lines <strong>2x+3y-8=0 , x -y +1=0<\/strong> and <strong>3x + y-5=0.<\/strong><\/p>\n<p><em><strong>Solution:<\/strong><\/em><\/p>\n<p><strong>a<sub>1<\/sub>=2, b<sub>1<\/sub>=3, c<sub>1<\/sub>=-8 , a<sub>2<\/sub>=1, b<sub>2<\/sub>=-1, c<sub>2<\/sub>=1<\/strong> and <strong>a<sub>3<\/sub>=3, b<sub>3<\/sub>=1, c<sub>3<\/sub>=-5.<\/strong><\/p>\n<p>Consider <strong>a<sub>3<\/sub> [b<sub>1<\/sub>c<sub>2<\/sub>-b<sub>2<\/sub>c<sub>1<\/sub>] + b<sub>3 <\/sub>[c<sub>1<\/sub>a<sub>2<\/sub>-c<sub>2<\/sub>a<sub>1<\/sub>] + c<sub>3 <\/sub>[a<sub>1<\/sub>b<sub>2<\/sub>-a<sub>2<\/sub>b<sub>1<\/sub>]<\/strong><\/p>\n<p><strong>= 3 (3 \u2013 8) + 1 (-8-2) + (-5) (-2-3)<\/strong><\/p>\n<p><strong>= -15 -10 + 25<\/strong><\/p>\n<p><strong>=0<\/strong><\/p>\n<p>Since the condition for concurrency is satisfied, the given lines are concurrent.<\/p>\n<p>Still need help with Mathematics? Please read more about our <a href=\"https:\/\/schooltutoring.com\/tutoring-programs\/math-tutoring\/\">Mathematics tutoring services<\/a>.<\/p>\n<p><span class=\"tutorOrange\">SchoolTutoring Academy<\/span> is the premier educational services company for K-12 and college students. We offer tutoring programs for students in K-12, AP classes, and college. To learn more about how we help parents and students in Parksville visit: <a href=\"\/\/schooltutoring.com\/tutoring-in-parksville-british%20columbia\/\u201d\">Tutoring in Parksville . <\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The point of intersection of two or more lines is a point which lies on all the given lies. It means the equations of all the given lines must be satisfied by the intersection point. This point of intersection of lines is called the \u201cpoint of concurrency\u201d.\u00a0 Finding this point of concurrency of two lines [&hellip;]<\/p>\n","protected":false},"author":19,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":""},"categories":[4,10],"tags":[538,846,849,2153,2200,2556],"class_list":["post-3289","post","type-post","status-publish","format-standard","hentry","category-calculus","category-geometry","tag-do-lines-on-graphs-cross","tag-how-do-you-calculate-on-graphs","tag-how-do-you-draw-lines","tag-what-does-concurrency-mean","tag-what-is-an-intersection","tag-when-do-lines-meet"],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/posts\/3289","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/users\/19"}],"replies":[{"embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/comments?post=3289"}],"version-history":[{"count":0,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/posts\/3289\/revisions"}],"wp:attachment":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/media?parent=3289"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/categories?post=3289"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/tags?post=3289"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}