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Zorluk: OrtaCircles

The circumference of a circular stained glass window is 18π18\pi inches. What is the area of the window in square inches?

(Enter only the numerical value that multiplies π\pi. For example, if the area is 10π10\pi, enter 10.)

Cevap: 81

Cevap

81
The correct answer is 81. First, the radius is found by dividing the circumference (18π18\pi) by 2π2\pi, which gives a radius of 9 inches. Then, the area is calculated by squaring this radius and multiplying by π\pi (92=819^2 = 81), resulting in a total area of 81π81\pi. Since the prompt asks for just the numerical value multiplying π\pi, the final response is 81.

Adım Adım Çözüm

1
Find the radius of the circular window using the circumference formula C=2πrC = 2\pi r.
18π=2πr⇒r=918\pi = 2\pi r \Rightarrow r = 9 inches.
The area formula requires the radius, so we must work backward from the given circumference to find it.
2
Calculate the area of the window using the area formula A=πr2A = \pi r^2.
A=π(9)2=81πA = \pi(9)^2 = 81\pi square inches.
Squaring the radius and multiplying by π\pi yields the total area of the circle.
3
Identify the requested numerical value.
81
The question specifically asks for the numerical coefficient that multiplies π\pi.

Anahtar Kavram

Calculating the area of a circle by first determining the radius from the circumference.
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