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Prime Time. Circle the seven prime numbers that, when added together, equal 75. 3, 11, 14, 13, 5, 17, 12, 6, 19, 23, 7, 9 Remember a prime number is a number that has only two factors, 1 and itself. 2 is prime : 1x2. Prime Time Solution. 3 + 5 + 7 + 11 + 13 + 17 + 19 = 75. Area of Circles.
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Prime Time • Circle the seven prime numbers that, when added together, equal 75. • 3, 11, 14, 13, 5, 17, 12, 6, 19, 23, 7, 9 • Remember a prime number is a number that has only two factors, 1 and itself. • 2 is prime : 1x2
Prime Time Solution • 3 + 5 + 7 + 11 + 13 + 17 + 19 = 75
Area of Circles Lesson 11-6
Review of Circles r d The radius of a circle is half of the diameter. Divide the diameter by 2 to get the radius.
Area of a Circle The area of a circle equals the product of pi () and the square of its radius. r Area = r²
Find the Area of the CircleRound the answer to the nearest tenth. • Area = r² • A = (4²) • A = (16) • A = 50.3 cm² 4 cm
Find the Area of the CircleRound the answer to the nearest tenth. • Area = r² • A = (8²) • A = (64) • A = 201.1 in² 8 in
Find the Area of the CircleRound the answer to the nearest tenth. • Area = r² • A = (5.5²) • A = (30.25) • A = 95.0 ft² 11 ft • Use the diameter to find the radius. • 11 ÷ 2 = 5.5 • Radius = 5.5 ft
Find the Area of the CircleRound the answer to the nearest tenth. • Area = r² • A = (3.25²) • A = (10.5625) • A = 33.2 m² 6.5 m • Use the diameter to find the radius. • 6.5 ÷ 2 = 3.25 • Radius = 3.25 m
Find the area to the nearest tenth. 25.6 m 9.8 in • Area = r² • A = (12.8²) • A = (163.84) • A = 514.7 m² • Area = r² • A = (9.8²) • A = (96.04) • A = 301.7 in²
Area of a Semi-Circle • Area = r² • A = (13²) • A = (169) • A = 530.9 ft² 26 ft • 530.9 ft² is the area of the whole circle. How can you find the area of half the circle. • Divide the area by 2. A semi- circle is half of a circle. • Answer: 265.5 ft²
Homework • Lesson 11-6 # 2-16 even • TEST: On Friday, lesson 11-5 (area of triangles and trapezoids), lesson 11-6 (area of circles), and lesson 11-7 (we will complete this tomorrow)