area of circle. take your notebook and folder from your cubby. then: joke of the day what do you get...
TRANSCRIPT
Take your notebook and folder from your cubby. Then:
JOKE of the DAYWhat do you get when you cross an insect with
the Easter bunny?Do Now
Find the RADIUS, DIAMETER, CIRCUMFERENCE, and AREA of the circle to the right
5cm
Take your notebook and folder from your cubby. Then:
JOKE of the DAYWhat do you get if you divide
the circumference of a jack-o-lantern by its diameter?Do Now
Find the RADIUS, DIAMETER, and CIRCUMFERENCE of the circle to the right
14ft
Agenda
• Do Now/ Hook: 5 min• Notes: 10 – 15 min• Explore: 15 min• Guided Practice: 15 min• Clean Up: 5 min
We are a TEAM of CONFIDENT PROBLEM SOLVERS & EFFECTIVE COMMUNICATORS2 minutes
Announcements
• HW Due Monday• Quiz
Tuesday/Wednesday• Tutoring Sign Ups• Tickets & Auction
FRIDAY
We are a TEAM of CONFIDENT PROBLEM SOLVERS & EFFECTIVE COMMUNICATORS2 minutes
Parts of a Circle – Review
Radius: Distance from the center to the edge of the circler = d/2
Diameter: Distance across the center of the circled = 2r
Circumference: Perimeter of circle, distance aroundFormula: C = 2 * r * π
Pi (π): Ratio of circumference to diameter. Always equals 3.14
Area: Space inside a figure. Formula for
circles: A = π * r2
Area Explore
1. Trace the circular item on your graph paper2. With a ruler, measure the radius of the circle (from
the center of the circle to the edge). Record your answer in inches in your notebook
3. Using the A = π * r2 formula, calculate the expected area of the circle. Record your answer in inches in your notebook
4. Look at how many square boxes make up the area of this circle. Estimate how many complete square boxes are inside the circle.
5. Compare the expected Area from the formula with the actual measured Area from Step 3
Whiteboard Practice• Show work• Use markers only for the math• Do not raise boards until I count to 3• Cap markers and flip boards over when we go
over problems
Question 1
What is the area of this circle?
A. 6 inches squaredB. 28.2 inches squaredC. 18.8 inches squaredD. 9.4 inches squared
A = π * r2
3in
Question 2
What is the area of this circle?
A. 144 π inches squaredB. 36 π inches squaredC. 6 π inches squaredD. 3 π inches squared
A = π * r2
6in
Question 3
What is the area of this circle?
A. 2463 feet squaredB. 22 feet squaredC. 44 feet squaredD. 153.9 feet squared
A = π * r2
14ft
Question 4
Khyren made a pizza with a diameter of 10 inches. What is the area of his pizza?
A. 78.5 inches squaredB. 314 inches squaredC. 17.2 inches squaredD. 25 inches squared
A = π * r2
Question 5
Mycynthia is building a circular bird pool in her backyard. If the distance from the center of the pool to the edge is 4ft, what is the area of the pool?
A. 25.1 feet squaredB. 50.3 feet squaredC. 16 feet squaredD. 12.6 feet squared A = π * r2