Radford University
Building a Recreation Center
It's all about location, location, location. Small groups work to find the best spot for a rec center to serve three different communities. Learners construct the inscribed and circumscribed circles of a triangle to find the best place....
Inside Mathematics
Circles in Triangles
Challenge the class with inscribed circles in triangles. The assessment task requests class members use their knowledge of circles and right triangles to prove two triangles are congruent. They go on to utilize their knowledge of...
EngageNY
Tangent Segments
What's so special about tangents? Learners first explore how if a circle is tangent to both rays of an angle, then its center is on the angle bisector. They then complete a set of exercises designed to explore further properties and...
EngageNY
Points of Concurrencies
You say that perpendicular bisectors intersect at a point? I concur! Learners investigate points of concurrencies, specifically, circumcenters and incenters, by constructing perpendicular and angle bisectors of various triangles.
Mathematics Vision Project
Geometric Figures
Logical thinking is at the forefront of this jam-packed lesson, with young mathematicians not only investigating geometric concepts but also how they "know what they know". Through each activity and worksheet, learners wrestle with...
Curated OER
Regents Exam Questions G.G.21: Centroid, Orthocenter, Incenter, and Circumcenter
In this triangles instructional activity, students solve 4 multiple choice problems. Students find the centroid, orthocenter, incenter, and circumcenter or various triangles.
Curated OER
Inscribing a Circle in a Triangle
Pupils investigate inscribing a circle in a triangle. They use Cabri Jr. to draw a triangle, locate the incenter, and use the distance from the incenter to a side of the triangle to inscribe a circle. The dynamic nature of the geometry...
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 lesson requires the use of Cabri, Jr.
Curated OER
Incenter of a Triangle
Tenth graders explore the properties of the incenter of a triangle. In this geometry lesson, 10th graders construct a triangle and the angle bisectors of each angle. The dynamic properties of Cabri Jr. allow students to locate and...
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: Incenter
MathWorld diagrams triangle with its incenter labeled and details how to find the incenter with links to the key terms. The site details many other interesting properties of the triangle incenter.
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.
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: Inscribing a Circle in a Triangle
In this activity, students bisect the angles of a triangle and find the incenter of the triangle. They find the distance from the incenter to the side of the triangle and use it as radius. With the incenter as the center, they inscribe a...
Math Planet
Math Planet: Geometry: More About Triangles
Explores triangles and related vocabulary through examples and a video lesson.
CK-12 Foundation
Ck 12: Geometry: Angle Bisectors in Triangles Intermediate
[Free Registration/Login may be required to access all resource tools.] This concept teaches students properties of angle bisectors and how to apply them.
Merriam-Webster
Merriam Webster: Dictionary Illustration: Incenter
A labeled illustration of an incenter inside a triangle.
Math Open Reference
Math Open Reference: Incircle
A complete reference guide to incircles. It provides definitions and examples that enhance further explanation. Includes links to related topics.
Math Open Reference
Math Open Reference: The Incircle of a Triangle
Learn about the incircle of a triangle with this handy reference guide. Provides a detailed definition, examples, 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.
Math Words
Mathwords: Inscribed Circles
Mathwords provides an explanation and a diagram of an inscribed circle. By clicking on any of the highlighted words, you will learn about related terms.
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.