Question

CHECKING YOUR UNDERSTANDING

Answer 1

Answer:

1) 81.67 cm² (Option A)

2) 28.26 m² (Option B)

3) 153.86 mi.² (Option D)

4) 329.90 m² (Option A)

5) 63.585 ft.² (Option C)

Step-by-step explanation:

GENERAL FORMULAES TO BE USED IN THIS QUESTION :-

Diameter of a circle with radius 'r' = 2r

Area of a circle with radius 'r' = πr²

SOLUTION :-

1) Diameter of the dinner plate = 10.2 cm

Radius of the dinner plate = 10.2/2 = 5.1 cm

⇒ Area of the circle = π(5.1)² = 26.01π cm² ≈ 81.67 cm²

2) Length of his leash = 3m

⇒ Area the dog has to run around = π(3)² = 9π m² = 28.26 m²

3) Radius of the circular range of storm = 7 mi.

⇒ Area of the circular range of storm = π(7)² = 49π mi.² = 153.86 mi.²

4) Diameter of carousel = 20.5 m

Radius of carousel = 20.5/2 = 10.25 m

⇒ Area of the carousel = π(10.25)² = 105.0625π m² ≈ 329.90 m²

5) Radius of the range of sprinkler = 4.5 ft.

⇒ Area of the range of sprinkler = π(4.5)² = 20.25π ft.² = 63.585 ft.²