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2 years ago

the area of a circle is 81 pi m^2. what is the circumference, in meters? express your answer in terms of pi.

Mathematics

1 answer:

mestny [16]2 years ago

8 0

<h3>Answer: 18pi</h3>

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Explanation:

The area 81pi square meters leads to the radius 9 meters

Use the formula A = pi*r^2 to see why this is the case. You plug in A = 81pi and solve for r to get r = 9.

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Once you know the radius, you can determine the circumference C

C = 2*pi*r

C = 2*pi*9

C = 2*9*pi

C = 18pi

The circumference is the perimeter, or distance, around the circle.

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a square painting has an area of 81x^2-90x-25. A second square painting has an area of 25x^2+30x+9. What is an expression that r

galina1969 [7]

Answer:

The answer in the procedure

Step-by-step explanation:

Let

A1 ------> the area of the first square painting

A2 ----> the area of the second square painting

D -----> the difference of the areas

we have

$A1=81x^{2}-90x-25$

$A2=25x^{2}+30x+9$

case 1) The area of the second square painting is greater than the area of the first square painting

The difference of the area of the paintings is equal to subtract the area of the first square painting from the area of the second square painting

D=A2-A1

$D=(25x^{2}+30x+9)-(81x^{2}-90x-25)$

$D=(-56x^{2}+120x+34)$

case 2) The area of the first square painting is greater than the area of the second square painting

The difference of the area of the paintings is equal to subtract the area of the second square painting from the area of the first square painting

D=A1-A2

$D=(81x^{2}-90x-25)-(25x^{2}+30x+9)$

$D=(56x^{2}-120x-34)$

4 0

3 years ago

A cylindrical rain barrel has a radius of 2 feet and holds a total of 30 cubic feet of water. How tall is the rain barrel? Use 3

enot [183]

Answer:

2.39 feet

Step-by-step explanation:

we know that

The volume of a cylinder is equal to

$V=\pi r^{2}h$

where

r is the radius of the base of the cylinder

h is the height of the cylinder

we have

$V=30\ ft^3$

$r=2\ ft$

$\pi =3.14$

substitute

$30=(3.14)(2^{2})h$

Solve for h

$30=(3.14)(4)h$

$h=30/12.56$

$h=2.39\ ft$

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Mars2501 [29]

By the binomial theorem,

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I assume you meant to say "independent", not "indecent", meaning we're looking for the constant term in the expansion. This happens for k such that

12 - 3k = 0 ===> 3k = 12 ===> k = 4

which corresponds to the constant coefficient

$\dbinom 64 (-1)^4 = \dfrac{6!}{4!(6-4)!} = \boxed{15}$

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