FW 3.2-3.3: Area of a Circle 1) Learning Target: I will find the area of a circle by estimating and squaring a circle. 2) HW: Inv. 2 Day 4 FW 3.2-3.3.

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FW 3.2-3.3: Area of a Circle 1) Learning Target: I will find the area of a circle by estimating and squaring a circle. 2) HW: Inv. 2 Day 4 FW 3.2-3.3 p. 14 SBAC Practice Test #2 Correct with the EDpuzzle 3) Warm Up: 1) Solve the equation: 2) Find the circumference if the radius is 4.5 in. Formula: C = d(3.14) d = 2r C = 2(4.5) (3.14) C = 9(3.14) C = 28.26 in. -3(m - 2) = 12 -3m + 6 = 12 - 6 = - 6 -3m = 6 ÷ -3 ÷ - 3 m = - 2

p. 12

To answer this question, the owner uses scale models of the different size pizzas: 9 in 4.5 in Approx. 64 in² 12 in 6 in Approx. 113 in² 15 in 7.5 in Approx. 177 in²

It should increase by about 81 inches to an area of 258 in². Approx. 64 in² 12 in 6 in Approx. 113 in² 15 in 7.5 in Approx. 177 in² As the diameter increases, the area increases. They are not increasing at a constant rate – as you increase the diameter by 3 inches each time, you do not increase the volume by the same amount each time (first you increase the area by about 49 inches, then you increase the area by about 64 inches). Teacher Note for Problem B2: Students might make a variety of estimates for the area of a circle with diameter 18 inches. Their estimates should be more than 64 square inches greater than the area of a pizza with diameter 15 inches, to account for the apparent increasing rate of area growth. The exact value for the area of a circle with diameter 18 inches is 81π square inches. This is approximately equal to 254 square inches. Very perceptive students might notice that the first increase in area was 49 and the next increase was 64, so the third increase might be 79. That is, in fact, approximately what happens. It illustrates the fact that, for quadratic functions, the second differences or differences of successive differences are constant (in this case the second differences are actually a bit more than 14 in every case). Students will study this topic in more detail in the Grade 8 UnitFrogs, Fleas, and Painted Cubes. It should increase by about 81 inches to an area of 258 in². If you calculate the price based on area, then the medium pizza should be priced at (113/64)($6.00), or about $10.60. The large pizza should be priced at (177/64)($6.00), or about $16.60.

FW 3.2: Area of a Circle Did I reach my Learning Target? I will find the area of a circle. Start Working on your Homework: Complete p. 15 in your packet And Correct with the KEY.