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Congruent Triangles 4.52 Importance of concurrency

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Triangle Points of Concurrency #1 Perpendicular bisectors and the circumcenter.

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Before we can talk about the circumcenters importance, we need some review on perpendicular bisectors. Circumcenter

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Review of Perpendicular Bisector Properties. Every point on the perpendicular bisector is equidistant from A and B.

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Therefore, the circumcenter is equidistant from each vertex. Why ?

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Since C is on each perpendicular bisector it is equidistant from each segments endpoint. Therefore…

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The equal distances are radii for a circle that is … written around (circumscribed) the circle. Ergo the term… Circumcenter.

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Why is this important? If A, B, and T are three cities, Point C is the ideal place to build a communication tower to broadcast to each city.

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Triangle Points of Concurrency #2 Angle bisectors and the Incenter.

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From any general point on the angle bisector, the perpendicular distance to either side is the same. Why ? P X Y

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The top angles are congruent by definition of angle bisector. There are two right angles are congruent by def. of perpendicular. P by the reflexive property of = ? ?By AAS X Y By CPCTC

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Each new point creates 2 congruent triangles by AAS. Why is this important ? Lets see.

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P Since the incenter P is on each angle bisector….

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P Point P is equidistant from each side. Remember, the distance from a point to a line is the brown perpendicular segment. Why is this important? Because these equal distances are radial distances.

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P The incenter generates an inscribed circle. Radial distances refer to a circle.

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Triangle Points of Concurrency #3 Medians and the Centroid.

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A median is a segment connecting the vertex to the midpoint of a side of a triangle.

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P The 3 medians meet at the centroid – point P.

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Each little triangle is unique, yet they all have something in common. What is it ?

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Since the areas of the little triangles around the centroid E are the same, … the triangle will balance on the centroid.

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Mobiles balance objects in an artistic form. Calders Mobile at the East Wing of the National Gallery of Art In Washington DC.

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Triangles balanced at their centroids.

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The birds are tied to their centers of balance or centroids.

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Triangle Points of Concurrency #4 Altitudes and the Orthocenter.

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Acute Triangle The point of concurrency is called… The Orthocenter

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Right Triangle The point of concurrency is called… The Orthocenter

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Obtuse Triangle Notice that although the altitudes are not concurrent…

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Obtuse Triangle The lines containing the altitudes are concurrent. The Orthocenter

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So what do you think is the importance or practical application of the orthocenter is? Nothing !!! It is just an interesting fact that mathematicians have discovered. Isnt this FUN !!! Psych

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Summary Line TypeConcurrency Point Importance Medians Altitudes Circumcenter Incenter Centroid Orthocenter Equidistant from the vertices Circumscribed Circle Equidistant from the sides Inscribed Circle Center of Balance None

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Cest fini. Good day and good luck. A Senior Citizen Production Thats all folks.

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