Texas Instruments
Texas Instruments: Math Today Wildfires Nearly Snuffed
Students can use the data to explore the relationship between area and perimeter for rectangles and circles and they will make generalizations about the shape of the rectangle that will produce the smallest perimeter.
The Math League
The Math League: Area and Perimeter
This tutorial provides a brief introduction about what area is, then gives the formulas for area of a square, rectangle, parallelogram, trapezoid, triangle, and circle. Examples of each formula are provided.
University of Regina (Canada)
University of Regina: Math Central: Irregular Surface Area Exercise
Students will be engaged by this assignment that has them estimating the areas of irregular surfaces. This includes computing the area of rectangles, triangles, and circles.
Math Open Reference
Math Open Reference: Circumference (Perimeter) of a Circle
Learn about the circumference of a circle with this helpful reference tool. Provides a detailed definition, examples, and an interactive activity that enhances further explanation. Includes links to related topics.
Math Open Reference
Math Open Reference: Radius of a Circle
Learn about the radius of a circle with this useful reference guide. Provides a detailed definition, examples, and an interactive activity that enhances further explanation. Includes links to related topics.
BBC
Bbc: Bitesize: Maths: 2 D Shapes
Learn about the properties of 2-D shapes: circles, triangles, polygons, and quadrilaterals. Includes information, video, and examples about each, with games and quizzes for reinforcement.
Math Open Reference
Math Open Reference: Polar Area
A complete reference guide to polar area. It provides definitions, examples. and an interactive activity that enhances further explanation. Includes links to related topics.
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: 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.
Khan Academy
Khan Academy: Circumference of a Circle
Find the circumference of a circle when given either the radius or diameter.Find the radius or diameter of a circle when given the circumference.Students receive immediate feedback and have the opportunity to try questions repeatedly,...
Math Open Reference
Math Open Reference: Semicircle
A handy reference guide to semicircles. It provides definitions and examples that enhance further explanation. Includes links to related topics.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Pi and the Area of Circles
Contains a question pertaining to finding the area of a circle.
Math Open Reference
Math Open Reference: Diameter
A complete reference guide to diameters. It provides definitions, examples, and interactive activities that enhance further explanation. Includes links to related topics.
Khan Academy
Khan Academy: Area and Circumference of Circles Challenge
Try these challenge problems involving area and circumference.
Khan Academy
Khan Academy: Area of a Sector
Relate the area of a sector to the area of a whole circle. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Khan Academy
Khan Academy: Circumference of a Circle
Practice finding the circumference of a circle.
Math Is Fun
Math Is Fun: Circle Sector and Segment
Learn about the "two main 'slices' of a circle" called a sector and a segment, and see how you can calculate the area of a sector or segment using trigonometry.
Khan Academy
Khan Academy: Circumference of Parts of Circles
Practice finding circumference of parts of circles.
Math Planet
Math Planet: Geometry: Parallelogram, Triangles Etc
Resource examines the area of geometric solids through examples and a video lesson. [0:39]
Mathematics Archives
Math Archives: Visual Calculus: Area of a Circle
Students will be able to use The Method of Exhaustion and find the area of a circle by illustrating graphically.
Free Math Help
Free Math Help: Area Formulas
The resource consists of area formulas and diagrams for a square, rectangle, circle, triangle, and trapezoid.
Rice University
Rice University: Cynthia Lanius: Circles Around Pythagoras
This site from the Rice University includes a fill-in-the-blank lesson on the definition of circles, as Pythagoras described.
Math Aids
Math Aids: Geometry
Great resource to practice and strengthen math skills pertaining to Geometry. Math worksheets are printable, may be customized, and include answer keys.