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You have a wire that is 20 cm long. You wish to cut it into two pieces. One piece will be bent into the shape of a square. The o

Aleksandr [31]

Answer:

Therefore the circumference of the circle is $=\frac{20\pi}{4+\pi}$

Step-by-step explanation:

Let the side of the square be s

and the radius of the circle be r

The perimeter of the square is = 4s

The circumference of the circle is =2πr

Given that the length of the wire is 20 cm.

According to the problem,

4s + 2πr =20

⇒2s+πr =10

$\Rightarrow s=\frac{10-\pi r}{2}$

The area of the circle is = πr²

The area of the square is = s²

A represent the total area of the square and circle.

A=πr²+s²

Putting the value of s

$A=\pi r^2+ (\frac{10-\pi r}{2})^2$

$\Rightarrow A= \pi r^2+(\frac{10}{2})^2-2.\frac{10}{2}.\frac{\pi r}{2}+ (\frac{\pi r}{2})^2$

$\Rightarrow A=\pi r^2 +25-5 \pi r +\frac{\pi^2r^2}{4}$

$\Rightarrow A=\pi r^2\frac{4+\pi}{4} -5\pi r +25$

For maximum or minimum $\frac{dA}{dr}=0$

Differentiating with respect to r

$\frac{dA}{dr}= \frac{2\pi r(4+\pi)}{4} -5\pi$

Again differentiating with respect to r

$\frac{d^2A}{dr^2}=\frac{2\pi (4+\pi)}{4}$ > 0

For maximum or minimum

$\frac{dA}{dr}=0$

$\Rightarrow \frac{2\pi r(4+\pi)}{4} -5\pi=0$

$\Rightarrow r = \frac{10\pi }{\pi(4+\pi)}$

$\Rightarrow r=\frac{10}{4+\pi}$

$\frac{d^2A}{dr^2}|_{ r=\frac{10}{4+\pi}}=\frac{2\pi (4+\pi)}{4}>0$

Therefore at $r=\frac{10}{4+\pi}$ , A is minimum.

Therefore the circumference of the circle is

$=2 \pi \frac{10}{4+\pi}$

$=\frac{20\pi}{4+\pi}$

4 0

3 years ago

If 1/4 gallons of water are enough to fill 7/10 of the pool how much water is nessacary to fill in the entire pool

anyanavicka [17]

<h3>Answer: 5/14 gallons</h3>

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Work Shown:

1/4 = 0.25

7/10 = 0.70 = 70%

We are told that 0.25 gallons of water fills 70% of the pool

We want to find how many gallons of water (call it x) are needed to fill 100% of the pool.

Set up the proportion below and solve for x

(0.25 gallons)/(70% filled) = (x gallons)/(100% filled)

0.25/70 = x/100

0.25*100 = 70x ....... cross multiply

25 = 70x

70x = 25

x = 25/70

x = (5*5)/(5*14)

x = 5/14 gallons

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An alternate method:

1/4 gallons = 7/10 pools filled

(10/7)*(1/4 gallons) = (10/7)*(7/10 pools filled)

(10*1)/(7*4) gallons = (10*7)/(7*10) pools filled

10/28 gallons = 1 pool filled

(5*2)/(14*2) gallons = 1 pool filled

5/14 gallons = 1 pool filled

In the second step, I multiplied both sides by 10/7 so that the "7/10" turns into "1".

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Yet another alternate method:

1/4 = 10/40

7/10 = 28/40

We need 10/40 gallons of water to fill 28/40 of one pool. We can multiply both fractions by 40 to indicate that 10 gallons of water will fill up 28 pools.

So we have this ratio

10 gallons : 28 pools

Dividing both parts by 28 tells us how many gallons are needed for one pool

10 gallons : 28 pools

10/28 gallons : 28/28 pools

10/28 gallons : 1 pool

5/14 gallons : 1 pool

8 0

3 years ago

Please help I need today

Serga [27]

Answer:

x = 62

Step-by-step explanation:

X and 62 are vertical angles and vertical angles are equal.

x = 62

3 0

3 years ago

Your health insurance premium is $4211 annually. If your employer pays 80% and you are paid monthly, how much is deducted from e

kakasveta [241]

<span>So if your annual monthly premium is $4211, to know how much you need to pay monthly so that would be: </span><span>$4211/12 = $350.92/month. Since your employer will be paying 80% of the amount, you will be paying the 20% of the amount monthly, so that would be .2(350.92) = $70.18/month</span>

5 0

3 years ago

Read 2 more answers

Approximate each irrational square root of 24

GREYUIT [131]

The answer is 4-5 cause it’s like 4.8 ish

5 0

3 years ago