 When three or more lines intersect at one point, 
they are concurrent. 
 The point at which they intersect is the point of 
concurrency.
 The perpendicular bisectors of the sides of a triangle 
are concurrent at a point equidistant from the 
VERTICES.
 The point of concurrency of the perpendicular 
bisectors of a triangle is called the circumcenter 
of the triangle. 
 Since the circumcenter is equidistant from the 
vertices, you can use the circumcenter as the 
center of the circle that contains each vertex of 
the triangle. 
 You would say the circle is circumscribed about the 
triangle.
 The circumcenter of a triangle can be inside, on, 
or outside the triangle.
 What are the coordinates of the circumcenter of the triangle 
with vertices P(0 , 6), O(0 , 0), and S(4 , 0)? 
 Find the intersection point of the triangle’s perpendicular 
bisectors. It is easiest to find the perpendicular bisectors of 
segment PO and segment OS.
 The bisectors of the angles of a triangle are 
concurrent at a point equidistant from the SIDES of 
the triangle.
 The point of concurrency of the angle bisectors 
of a triangle is called the incenter of the 
triangle. 
 The incenter is ALWAYS inside the triangle.
 GE = 2x – 7 and GF = x + 4. What is GD? 
 G is the incenter of the triangle. 
GE = GF 
2x – 7 = x + 4 
x = 11 
GF = 11 + 4 
= 15 
Since GF = GD, GD = 15.
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Fair use is a use permitted by copyright 
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Geometry unit 5.3

  • 2.
     When threeor more lines intersect at one point, they are concurrent.  The point at which they intersect is the point of concurrency.
  • 3.
     The perpendicularbisectors of the sides of a triangle are concurrent at a point equidistant from the VERTICES.
  • 4.
     The pointof concurrency of the perpendicular bisectors of a triangle is called the circumcenter of the triangle.  Since the circumcenter is equidistant from the vertices, you can use the circumcenter as the center of the circle that contains each vertex of the triangle.  You would say the circle is circumscribed about the triangle.
  • 5.
     The circumcenterof a triangle can be inside, on, or outside the triangle.
  • 6.
     What arethe coordinates of the circumcenter of the triangle with vertices P(0 , 6), O(0 , 0), and S(4 , 0)?  Find the intersection point of the triangle’s perpendicular bisectors. It is easiest to find the perpendicular bisectors of segment PO and segment OS.
  • 7.
     The bisectorsof the angles of a triangle are concurrent at a point equidistant from the SIDES of the triangle.
  • 8.
     The pointof concurrency of the angle bisectors of a triangle is called the incenter of the triangle.  The incenter is ALWAYS inside the triangle.
  • 9.
     GE =2x – 7 and GF = x + 4. What is GD?  G is the incenter of the triangle. GE = GF 2x – 7 = x + 4 x = 11 GF = 11 + 4 = 15 Since GF = GD, GD = 15.
  • 10.
    All rights belongto their respective owners. Copyright Disclaimer Under Section 107 of the Copyright Act 1976, allowance is made for "fair use" for purposes such as criticism, comment, news reporting, TEACHING, scholarship, and research. Fair use is a use permitted by copyright statute that might otherwise be infringing. Non-profit, EDUCATIONAL or personal use tips the balance in favor of fair use.