Curated OER
Opposite Angles in a Cyclic Quadrilateral
Learners investigate cyclic quadrilaterals in this geometry lesson. They use Cabri Jr to explore the sum of the measures of opposite angles in a cyclic quadrilateral. The dynamic nature of Cabri allows young scholars to form and verify...
Curated OER
Circumscribing a Circle About a Triangle
Pupils circumscribe a circle about a triangle. They construct a triangle using Cabri Jr and then circumscribe it. They then use knowledge of perpendicular bisectors and circumcenters to locate the center of the circle and then...
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
Inscribed Quadrilaterals and Parallelograms
Students differentiate between inscribed quadrilaterals and parallelograms. In this geometry lesson, students identify the shaped of the polygons when it is inscribed inside of a circle. They calculate the missing angles of the inscribed...
Maths Challenge
Maths challenge.net: Circular Pipes
A realistic world problem using the knowledge of chords and the parts of a circle to solve. Test your knowledge on this brain teaser!
Maths Challenge
Maths challenge.net: Triangle in a Square
A "three star" geometry problem requiring some prior knowledge in math and proofs to maximize the area of an inscribed triangle in terms of the hypotenuse.
Maths Challenge
Maths challenge.net: Inscribed Rectangle
This is a proof problem, considered a "three star" geometry problem requiring knowledge of proofs and properties of circles to solve this equal area of inscribed polygons problem.
Maths Challenge
Maths challenge.net: Three Circles
This is a proof problem, considered a "three star" geometry problem requiring knowledge of proofs and properties of circles.
Maths Challenge
Maths challenge.net: Annulus
An annulus of a circle is defined and then a proof like problem is posed involving area and radius of circles.
Maths Challenge
Maths challenge.net: Maximum Square
A challenging proof like geometry of finding the square inscribed in a triangle.
Maths Challenge
Maths challenge.net: Isosceles Trapezium
This is a "three star" geometry problem where prior knowledge of problem solving and thinking through proofs is recommended to solve this trapezoid inscribed in a semicircle problem.
Maths Challenge
Maths challenge.net: Rectangular Circles
An area problem involving finding the area of a rectangle and a circle. The problem may be made into a general proof as well.
Maths Challenge
Maths challenge.net: Lunes
A "three star" geometry problem where some experience of math problem solving skills and knowledge of circles is recommended to solve this lunes (parts of a circles) area problem
Texas Education Agency
Texas Gateway: Making and Verifying Conjectures About Circles
Given information about the relationship(s) witnin one circle or a set of circles, the student will explore special segments and angles of circles.
Math Open Reference
Math Open Reference: Constructions
Learn about drawing shapes using only a compass and straight edge or ruler with out measuring any lengths or angles.
Cuemath
Cuemath: Equilateral
Learn all about the basic properties of equilateral. This lesson targets the meaning of equilateral, shows how to construct equilateral shapes, explores some of the equilateral shapes and properties, and how to apply them while solving...
National Council of Teachers of Mathematics
The Math Forum: Elementary Geometry Circles
The Math Forum offers an archive of question and answer sessions on circles and how they relate to geometry.
Texas Instruments
Texas Instruments: Relation Between Central Angle and Inscribed Angle Measure
Students investigate the relationship between measure of central and inscribed angles in a circle.
Texas Instruments
Texas Instruments: Going in Circles Inscribed Angles
This lesson has students discover properties of inscribed angles in a circle. Students use the Geometer's Sketchpad application for the TI-89 to construct a circle and an inscribed angle.
Texas Instruments
Texas Instruments: Relationship of Angles to the Circle
For this activity, students recognize the relationship of angles to circles. They study the Inscribed Angle Theorem and its corollaries.
Texas Instruments
Texas Instruments: Central Versus Inscribed Angles in Circles
Using Cabri Jr. to explore the connection between central and inscribed angles along with their arc measure.
Texas Instruments
Texas Instruments: Angles in Circles
The student will use the Cabri Jr. APP to discover the relationship between inscribed and central angles in a circle.
Texas Instruments
Texas Instruments: Cabri Jr. Inscribed and Central Angles
This activity uses Cabri Jr. to explore the relationship between inscribed and central angles subtended from the same arc of a circle.
Texas Instruments
Texas Instruments: Angle Bisectors and Medians of Quadrilaterals
In this activity, students will construct angle bisectors and medians in quadrilaterals and explore the properties that appear to be true for four-sided figures. They may find it necessary to review the definitions and properties of...