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| ** [https://www.urbanpro.com/cbse-class-9-maths-construction UrbanPro] : This website gives downloadable worksheets with problems on triangle construction. | | ** [https://www.urbanpro.com/cbse-class-9-maths-construction UrbanPro] : This website gives downloadable worksheets with problems on triangle construction. |
| ** [https://schools.aglasem.com/59755 AglaSem Schools] : This website lists important questions for math constructions. | | ** [https://schools.aglasem.com/59755 AglaSem Schools] : This website lists important questions for math constructions. |
| + | ** [http://www.nios.ac.in/media/documents/SecMathcour/Eng/Chapter-12.pdf National Institute of Open Schooling]: This website has good reference notes on concurrency of lines in a triangle for both students and teachers. |
| + | ** [http://www.mathopenref.com/ Math Open Reference] : This website gives activities that can be tried and manipulated online for topics on geometry. |
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| * Books and journals | | * Books and journals |
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| Constructing a unique triangle with perimeter and with other two parameters the base angles of the triangle follows construction on a triangle using SAS congruence rule. | | Constructing a unique triangle with perimeter and with other two parameters the base angles of the triangle follows construction on a triangle using SAS congruence rule. |
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− | ==== Concept #: [[Concurrency in triangles]] ==== | + | ==== Concept #: Concurrency in triangles ==== |
− | Concurrent lines are three or more lines that intersect at the same point. The mutual point of intersection is the point of concurrency
| + | A set of lines are said to be concurrent if they all intersect at the same point. In the figure below, the three lines are concurrent because they all intersect at a single point P. The point P is called the "point of concurrency". This concept appears in the various centers of a triangle. |
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| + | [[File:concurrent lines.jpeg|100px|link=http://karnatakaeducation.org.in/KOER/en/index.php/File:Concurrent_lines.jpeg]] |
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| + | All non-parallel lines are concurrent. |
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| + | Rays and line segments may, or may not be concurrent, even when not parallel. |
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| In a triangle, the following sets of lines are concurrent: | | In a triangle, the following sets of lines are concurrent: |