180 likes | 331 Views
Find the circumference and area of circles. circle. center radius diameter circumference pi. Lesson 1 MI/Vocab. Lesson 1 Key Concept 1. ×. . Use a calculator to find 5 . 5 15.70796327. ENTER. =. Find the Circumferences of Circles.
E N D
Find the circumference and area of circles. • circle • center • radius • diameter • circumference • pi Lesson 1 MI/Vocab
× Use a calculator to find 5. 5 15.70796327 ENTER = Find the Circumferences of Circles Find the circumference of the circle. Round to the nearest tenth. C = d Circumference of a circle C = 5Replace d with 5. C = 5 This is the exact circumference. Answer: The circumference is about 15.7 feet. Lesson 1 Ex1
Find the circumference of the circle. Round to the nearest tenth. • A • B • C • D A. 38.5 in. B. 31.4 in. C. 22.0 in. D. 19.7 in. Lesson 1 CYP1
Find the Circumferences of Circles Find the circumference of the circle. Round to the nearest tenth. C = 2r Circumference of a circle C = 2 3.8 Replace r with 3.8. C ≈ 23.9 Use a calculator. Answer: The circumference is about 23.9 meters. Lesson 1 Ex2
Find the circumference of the circle. Round to the nearest tenth. • A • B • C • D A. 9.4 m B. 11.3 m C. 18.5 m D. 22.6 m Lesson 1 CYP2
Find the Areas of Circles Find the area of the circle. Round to the nearest tenth. A = r2 Area of a circle A = 32 Replace r with 3. A = 9 Evaluate 32. A ≈28.3 Use a calculator. Answer: The area is about 28.3 square yards. Lesson 1 Ex3
Find the area of the circle. Round to the nearest tenth. • A • B • C • D A. 12.6 ft2 B. 14.1 ft2 C. 15.3 ft2 D. 17.4 ft2 Lesson 1 CYP3
Find the Areas of Circles Find the area of the circle. Round to the nearest tenth. A = r2 Area of a circle A = 52 Replace r with half of 10 or 5. A = 25 Evaluate 52. A ≈78.5 Use a calculator. Answer: The area is about 78.5 square inches. Lesson 1 Ex4
Find the area of the circle. Round to the nearest tenth. • A • B • C • D A. 42.7 cm2 B. 50.3 cm2 C. 52.1 cm2 D. 54.6 cm2 Lesson 1 CYP4
POOLSThe Patels have a circular pool with a radius of 12 feet. They plan on installing a 4-foot-wide walkway around the pool. What will be the area of the walkway? To determine the area of the walkway, you must subtract the area of the pool from the area of the outer circle that includes the pool and the walkway. Lesson 1 Ex5
Area of Outer Circle A = r2 Area of a circle A = (16)2 Replace r with 12 + 4 or 16. A = 256 Evaluate 162. Lesson 1 Ex5
Area of Pool A = r2 Area of a circle A = 122 Replace r with 12. A = 144 Evaluate 122. Lesson 1 Ex5
Area of Walkway = Area of Outer Circle – Area of Pool ≈ 256 – 144 ≈ 351.9 Answer: The area of the walkway is about 351.9 square feet. Lesson 1 Ex5
POOLS The Shoemakers have a circular pond with a radius of 4 feet. They plan on installing a 2-foot-wide walkway around the pond. What will be the area of the walkway? • A • B • C • D A. 62.8 ft2 B. 84.3 ft2 C. 99.2 ft2 D. 113.1 ft2 Lesson 1 CYP5