CK-12 Foundation
Ck 12: Geometry: Areas of Combined Figures Involving Circles
[Free Registration/Login may be required to access all resource tools.] In this lesson studednts find the areas of combined figures involving parts of circles. Students examine guided notes, review guided practice, watch instructional...
Sophia Learning
Sophia: Sector Area of a Circle: Lesson 2
This lesson will demonstrate how to find the area and radius of a circle when given the sector area and central angle measure. It is 2 of 8 in the series titled "Sector Area of a Circle."
Sophia Learning
Sophia: Sector Area of a Circle: Lesson 4
This lesson will demonstrate how to find the area and radius of a circle when given the sector area and central angle measure. It is 4 of 8 in the series titled "Sector Area of a Circle."
Calculator Soup
Calculator Soup: Circle Calculator
Use this circle calculator to find the area, circumference, radius, or diameter of a circle. Given any one variable A, C, r or d of a circle you can calculate the other three unknowns.
Varsity Tutors
Varsity Tutors: Hotmath: Review: Area
Find a quick, concise explanation of area and the formulas for different shapes. An example is given to help you understand how find the area of a shape. The area formulas are listed for different types of shapes.
Science Struck
Science Struck: Cross Sectional Area of a Cylinder
Presents the formula and an example showing how to find the cross-sectional area of a cylinder. In this case, it is the same as the surface area for the circular faces.
ClassFlow
Class Flow: Circles
[Free Registration/Login Required] This flipchart has information and practice regarding finding area and circumference of circles.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Area of a Cone
This question and answer site is about finding the area of a cone when the height and the angle at the convergence point are given. The site goes on to explain how a cone relates to a circle.
Illustrative Mathematics
Illustrative Mathematics: 8.g Areas of Geometric Shapes With the Same Perimeter
Eighth graders are shown three polygons with equal sides and a circle. They are asked to find the area of each when the perimeter is one unit and to order them from smallest area to largest. Aligns with 8.G.B.7.
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.
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.
Wolfram Research
Wolfram Math World: Chord
Describes what a chord is and shows a diagram and shows how to find areas using integral calculus.
Math Words
Math Words: Right Circular Cylinder
Find a picture of a right circular cylinder here with the formulas for volume, total surface area, and lateral surface area. Site by MathWords.com.
Texas Instruments
Texas Instruments: Numb3 Rs: Meltdown
Based off of the hit television show NUMB3RS, this lesson has students explore the relationship between a circle's area and it's radius. This is framed in the context of a scene in where a pile of ice is melting into an increasingly...
Science and Mathematics Initiative for Learning Enhancement (SMILE)
Smile: The Area of a Circle
An investigative approach is given to exploring finding the area of a circle.
Curated OER
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.
Texas Education Agency
Texas Gateway: Applying Geometric Probability
The student will find the area of polygons and circles. Then, the student will use probablity to solve real-world problems.
Khan Academy
Khan Academy: Radius and Diameter
Practice problems finding radius and diameter of a circle.
Sophia Learning
Sophia: Determining Unknown Values Using the Volume of a Cylinder
This video lesson demonstrates how to work backward and use the volume of a cylinder to find an unknown value such as the radius or height. Students can check their understanding with an assessment. [4:41]
Curated OER
Web Math: Find Out Things About Circles
WebMath offers a great site for students to practice finding the diameter, area and circumference of a circle.
Shodor Education Foundation
Shodor Interactivate: Single Fraction Pointer
Determine the value of a given fraction represented as a point on a number line. Then find a fraction whose value is the given fraction using an arrow on the number line as a guide.
Analyze Math
Analyze Math: Polygons Problems
Here are four problems about the area of a regular polygon. Start by finding the area of a hexagon inscribed in a circle of radius 10, and end by proving that as the number of sides of the polygon increases, the area of the polygon...
PBS
Pbs Learning Media: Square Wheeled Tricycle: Radius and Circumference
This interactive exercise focuses on working with the radius of various circles to find the circumference and area as well as challenging you to find the distance a square wheel travels around the track.
Khan Academy
Khan Academy: Radius and Diameter
Practice finding the radius and diameter of a circle using both vocabulary and visuals. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.