Curated OER
Regents Exam Questions G.G.21: Centroid, Orthocenter, Incenter, and Circumcenter
In this triangles worksheet, high schoolers solve 4 multiple choice problems. Students find the centroid, orthocenter, incenter, and circumcenter or various triangles.
Curated OER
Exploring the Circumcenter of a Triangle
Young scholars construct the circumcenter of a triangle. In this constructing the circumcenter of a triangle lesson, students construct a triangle using Cabri Jr. Young scholars draw perpendicular bisectors of the sides of the triangle....
Curated OER
Properties of the Centers of a Triangle
High schoolers investigate properties of the four centers of a triangle and explore a special property of the circumcenter and orthocenter of a triangle. This instructional activity requires the use of Cabri, Jr.
Curated OER
Standardized Geometry Test Practice
In this angles, lines and figures review instructional activity, 10th graders solve and complete 33 standardized multiple choice problems. First, they use the Segment Addition Postulate to solve for a variable given an equation for each...
Curated OER
Concurrence
In this concurrence worksheet, 10th graders solve 10 different problems related to determining various concurrences. First, they determine which type of triangle has two altitudes outside of it. Then, students determine the distance...
Cuemath
Cuemath: Point of Concurrency
Learn all about the point of concurrency. This lesson targets the point of concurrency of perpendicular bisectors, the point of concurrency of the angle bisectors of a triangle, and has interesting solved examples and practice questions.
Wolfram Research
Wolfram Math World: Perpendicular Bisector
MathWorld's definition of a perpendicular bisector, with illustrations to show the different uses of the perpendicular bisector.
Texas Instruments
Texas Instruments: Numb3 Rs: Slippery Paths
Based off of the hit television show NUMB3RS, this lesson introduces students to Steiner Points, which are essentially points of concurrency within triangles. This is done in the context of a criminal who needs to place a hideout...
Texas Instruments
Texas Instruments: Centers of a Triangle
The centroid, circumcenter, orthocenter, and incenter are the four classic centers of a triangle that are studied in geometry. In this activity, you will construct these center points and discover their properties. [Requires Adobe Reader.]
Texas Instruments
Texas Instruments: Circumcenter and Incenter
In this activity, students examine the location of the circumcenter and incenter for different triangles.
Texas Instruments
Texas Instruments: Circumscribing a Circle About a Triangle
In this activity, students use the distance of the circumcenter of a triangle to each vertex of the triangle as the radius and draw a circle using the circumcenter as the center.
Texas Instruments
Texas Instruments: Numb3 Rs: Location! Location! Location!
Based off of the hit television show NUMB3RS, this lesson introduces students to Voronoi diagrams, which split a plane into regions corresponding to distances to given points. The lesson is framed in the context of splitting a city into...
Ministry of Education and Universities of the Region of Murcia (Spain)
Ministerio De Educacion Y Ciencia: Rectas Notables De Un Triangulo
In Spanish. Interactive activities dealing with the concept of angle bisector, median and altitude of a triangle. A description of the circumcenter and centroid are given along with a visual representation. [Requires Java.]
Ministry of Education and Universities of the Region of Murcia (Spain)
Ministerio De Educacion Y Ciencia: Actividades Con Las Rectas De Un Triangulo
You will find an interactive activity to review the following concepts: altitude, median, angle bisector and points of concurrency in triangles. Five different interactive quizzes are also provided to test your knowledge.
Texas Instruments
Texas Instruments: Exploring the Circumcenter of a Triangle
In this activity, students develop an understanding of the circumcenter of a triangle. Students construct perpendicular bisectors of three sides of a triangle and find the circumcenter.
Math Planet
Math Planet: Geometry: More About Triangles
Explores triangles and related vocabulary through examples and a video lesson.
Varsity Tutors
Varsity Tutors: Hotmath: Graphing Calculator Practice: Polygons and Area of Plane Figures
Practice using your graphing calculator for measuring and constructing polygons and other plane figures. If you get stumped or if you would like to check your work, then select the View Solution button, which is located directly under...
Illustrative Mathematics
Illustrative Mathematics: G C Inscribing a Triangle in a Circle
This problem introduces the circumcenter of a triangle and shows how it can be used to inscribe the triangle in a circle. It also shows that there cannot be more than one circumcenter. Aligns with G-C.A.3.
Illustrative Mathematics
Illustrative Mathematics: G C Circumcenter of a Triangle
The goal of this task is to construct the circumcenter of a triangle, that is, the point which is the same distance from each of the triangle's three vertices. This task shows that the three perpendicular bisectors of the sides of a...
Other
Gobierno De Navarra: Puntos Y Rectas Notables De Un Triangle
Learn how to construct the bisectors, median and altitude of a triangle.
Math Open Reference
Math Open Reference: Euler Line
Learn about the Euler line with this handy reference guide. Provides a detailed definition and an interactive activity that enhances further explanation. Includes links to related topics.
CK-12 Foundation
Ck 12: Interactive Geometry: 4.5 Theorems About Concurrence in Triangles
Find out about some common centers of triangles.
Other
University of Evansville: Encyclopedia Triangle Centers
This site contains a comprehensive study of triangle centers. Seems more for an advanced level. Provides a list of six links to 1114 centers.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Triangle Centers: Etymologies
At this page you will find Dr. Math responding to an inquiry about the relevance of the names of each of the special triangle centers.