# Using the formula C = 2πr, find the circumference of a circle with diameter of 28 inches.?

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Thanx 4 the help

• There are two ways to find the circumference of a circle. One way is 2πr, where r is the radius, or πd, where d is the diameter. Both ways are the same because a radius is equal to a diameter. Using 2πr,

we first divide 48 by 2, which is 24, the radius. The formula is now C = 2π(24) Multiply 24 and 2 and you get 48. 48 * π is 48π.

• as radius is half of diameter, r = d/2 where d is diameter of the circle

now in the formula C = 2πr we can put d/2 at the place of r because r=d/2

now formula becomes C = 2π(d/2) = 2 * 22/7 * 28 = 132 inches

i have explained in the easiest way i can..

Source(s): my mind
• diameter = 2 times radius

d = 2r

2r = 28 inches

r = 28/2 inches

r = 14 inches.

C = 2πr = 2π * 14 = 28π inches.

so radius = 28/2 = 14

Circumference = 2 x pi x 14 = 28 pi

or from calculator = 87.96 inches ….correct to 2 decimal places

• Circumference: = 2(22/7)(18/2) = 2(22/7)(9) = 396/7 or fifty six 4/7 reply: 56 4/7 inches discipline: = 22/7(18/2)² = 22/7(9)² = 22/7(81) = 1,782/7 or 254 4/7 reply: 254 four/7 rectangular inches

• r = d/2

C = 2πr = 2πd/2 2π28/2 = 28π inches

• Everybody the answer is (88)

Oh okay. pi= 3.14 x 2 = 6.28. 6.28 x 14 = 87. 92. ANSWER 88 😀 right. Round to the nearest 10 which is 88 🙂

• 48π

• 87.964594300514210676954014731826 inches

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