All categories

3 years ago

The radius of a circle is 7 miles. What is the circumference?

Mathematics

1 answer:

Fiesta28 [93]3 years ago

4 0

The circumference is ~43.98 miles.

You might be interested in

A cylindrical can without a top is made to contain 25 3 cm of liquid. What are the dimensions of the can that will minimize the

Basile [38]

Answer:

Therefore the radius of the can is 1.71 cm and height of the can is 2.72 cm.

Step-by-step explanation:

Given that, the volume of cylindrical can with out top is 25 cm³.

Consider the height of the can be h and radius be r.

The volume of the can is V= $\pi r^2h$

According to the problem,

$\pi r^2 h=25$

$\Rightarrow h=\frac{25}{\pi r^2}$

The surface area of the base of the can is = $\pi r^2$

The metal for the bottom will cost $2.00 per cm²

The metal cost for the base is =$(2.00× $\pi r^2$ )

The lateral surface area of the can is = $2\pi rh$

The metal for the side will cost $1.25 per cm²

The metal cost for the base is =$(1.25× $2\pi rh$ )

$=\$2.5 \pi r h$

Total cost of metal is C= 2.00 $\pi r^2$ + $2.5 \pi r h$

Putting $h=\frac{25}{\pi r^2}$

$\therefore C=2\pi r^2+2.5 \pi r \times \frac{25}{\pi r^2}$

$\Rightarrow C=2\pi r^2+ \frac{62.5}{ r}$

Differentiating with respect to r

$C'=4\pi r- \frac{62.5}{ r^2}$

Again differentiating with respect to r

$C''=4\pi + \frac{125}{ r^3}$

To find the minimize cost, we set C'=0

$4\pi r- \frac{62.5}{ r^2}=0$

$\Rightarrow 4\pi r=\frac{62.5}{ r^2}$

$\Rightarrow r^3=\frac{62.5}{ 4\pi}$

⇒r=1.71

Now,

$\left C''\right|_{x=1.71}=4\pi +\frac{125}{1.71^3}>0$

When r=1.71 cm, the metal cost will be minimum.

Therefore,

$h=\frac{25}{\pi\times 1.71^2}$

⇒h=2.72 cm

Therefore the radius of the can is 1.71 cm and height of the can is 2.72 cm.

6 0

3 years ago

.Divide the sum of 13/5 and -12/7 by the product of -31/7 and -(1/2)

andre [41]

Answer:

hello u so cool i admire you <3

6 0

3 years ago

Read 2 more answers

maria works as a florist and worked for 8 hours last week and earned 98$ at that rate how much will she earn this weekend if she

olga_2 [115]

$171.50

$98 ÷ 8 = $12.25 per hour

$12.25 x 14 = $171.50

7 0

3 years ago

Read 2 more answers

a lighthouse casts a 128 footshadow a nearby lampost that measures 5 feet 3inches cast an 8 Foot Shadow

k0ka [10]

5 times 3 times 8 is the correct answer, because it's like finding the volume.<span />

8 0

3 years ago

− 4 x + 12 −4x+12 y=x

Lelu [443]

Answer:

3x-4y=4

Step-by-step explanation:

7 0

2 years ago