Paul Dawkins
Paul's Online Notes: Algebra: Graphing and Functions
Students investigate functions and graphing. Topics examined are lines, circles, graphing functions, inverse functions, and combining functions. Class notes, definitions, and examples with detailed solutions are included. The class notes...
Oswego City School District
Regents Exam Prep Center: Area of Polygons and Circles
How would you find the area of a polygon or circle? Explore this concept with engaging activities at this test prep site. Here you will find detailed problem solving strategies with accompanying visuals, a reference table with formulas,...
National Council of Teachers of Mathematics
The Math Forum: Analytic Geometry: Polar Coordinates
This site from The Math Forum provides great information on polar coordinates. You can access this information either by clicking on the coordinates link or just scrolling down, it is the first one listed on the page. Includes several...
Analyze Math
Analyze Math: Inscribed and Central Angles in Circles
The geometry tutorial investigates the definitions and theorems related to inscribed and central angles in circles. An example with a detailed solution is included.
Johan Claeys
Math Abundance: The Circle: Basic Concepts
Goes over the equation of a circle, parametric equations of a circle, intersection of circle and line, tangent line in a point of a circle, etc.
Purple Math
Purplemath: Completing the Square: Circle Equations
This tutorial works through two examples step by step that shows how to complete the square for finding the center and radius of a circle.
Walter Fendt
Walter Fendt: Apps on Mathematics
Apps for Arithmetic, Plane Geometry, and other Geometry concepts are provided.
University of Cambridge
University of Cambridge: Maths and Sports: Olympic Rings
This activity explores shapes and circles by encouraging children to look really hard at something they will see very often in the run-up to London 2012, and is designed to be accessible to primary pupils at Key Stage 1.
Khan Academy
Khan Academy: Angles in Circles
Practice measuring angles using a circle protractor, solve problems about angles as part of a circle. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Illustrative Mathematics
Illustrative Mathematics: G Co Seven Circles Ii
In this task, seven pennies are placed in a circle so that they are all touching one in the center and their neighbors. Learners are asked to find as many rigid motions of the plane as they can which are symmetries of this configuration...
Illustrative Mathematics
Illustrative Mathematics: G Co, G Srt Seven Circles I
In this task, seven pennies are placed in a circle so that they are all touching one in the center and their neighbors. The question is whether this will work with other equally-sized circles. Aligns with G-SRT.C and G-CO.C.10.
Illustrative Mathematics
Illustrative Mathematics: G Gpe Slopes and Circles
The purpose of this task is to lead young scholars through an algebraic approach to a well-known result from classical geometry, namely, that a point X is on the circle of diameter AB whenever angle AXB is a right angle. This consists of...
University of St. Andrews (UK)
University of St. Andrews: James Gregory
This site, which is provided for by the University of St. Andrews, contains information on the mathematician Gregory and his accomplishments.
Math Open Reference
Math Open Reference: Circles
A complete reference guide to circles including parts, angles, and arcs. It provides definitions and interactive activities that enhance further explanation.
CK-12 Foundation
Ck 12: Geometry: Segments From Secants
[Free Registration/Login may be required to access all resource tools.] Apply the Two Secants Segments Theorem.
CK-12 Foundation
Ck 12: Elem Math: Identifying Semi Circles and Quarter Circles
[Free Registration/Login may be required to access all resource tools.] The video defines a semi-circle and a quarter-circle and answers a question determining which object is a semi-circle. The video is followed by a series of practice...
CK-12 Foundation
Ck 12: Geometry: Arcs in Circles
[Free Registration/Login may be required to access all resource tools.] In this lesson students apply the properties of arcs and central angles. Students examine guided notes, review guided practice, watch instructional videos and...
CK-12 Foundation
Ck 12: Elem Math: Counting Semi Circles and Quarter Circles in Composite Figures
[Free Registration/Login may be required to access all resource tools.] The video defines composite figures, semi-circles, and quarter circles, then uses those definitions to determine how many semi-circles and quarter circles are in the...
CK-12 Foundation
Ck 12: Geometry: Properties of a Circle Study Guide
[Free Registration/Login may be required to access all resource tools.] This study guide reviews the terminology for circles (tangent, arcs, central angles) and the equation for a circle.
Mathigon
Mathigon: Geometry: Circle and Pi: Introduction
This lesson focuses on the characteristics of a circle including similarity, radius, circumference, and Pi. It provides formulas to determine the area of a circle, calculating Pi, and learning exercises throughout.
CK-12 Foundation
Ck 12: Geometry: Radius or Diameter of a Circle Given Area
[Free Registration/Login may be required to access all resource tools.] Find the radius or diameter of a circle given its area.
CK-12 Foundation
Ck 12: Geometry: Radius or Diameter of a Circle Given Area
[Free Registration/Login may be required to access all resource tools.] Find the radius or diameter of a circle given the area of the circle
CK-12 Foundation
Ck 12: Geometry: Angles Outside a Circle
[Free Registration/Login may be required to access all resource tools.] Solve problems containing angles outside a circle.
CK-12 Foundation
Ck 12: Geometry: Arc Length
[Free Registration/Login may be required to access all resource tools.] In this lesson students find the length of an arc. Students examine guided notes, review guided practice, watch instructional videos and attempt practice problems.