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MA_775_DIABLO [31]
3 years ago
5

A piece of wire of length L will be cut into two pieces, one piece to form a square and the other piece to form an equilateral t

riangle. How should the wire be cut so as to: (a) Maximize the sum of the areas of the square and the triangle? (b) Minimize the sum of the areas of the square and the triangle?
Mathematics
1 answer:
inn [45]3 years ago
5 0

Answer:

  (a)  square: L; triangle: 0.

  (b)  square: L·(-16+12√3)/11; triangle: L·(27-12√3)/11

Step-by-step explanation:

<u>Strategy</u>: First we will write each area in terms of its perimeter. Then we will find the total area in terms of the amount devoted to the square. Differentiating will give a way to find the minimum total area.

__

In terms of its perimeter p, the area of a square is ...

  A_square = p^2/16

In terms of its perimeter p, the area of an equilateral triangle is ...

  A_triangle = p^2/(12√3)

Then the total area of the two figures whose total perimeter is L with "x" devoted to the square is ...

  A_total = x^2/16 + (L-x)^2/(12√3)

__

(a) We know when polygons are regular, the one with the most area for the least perimeter is the one with the most sides. Hence, the total area is maximized when all of the wire is devoted to the square.

__

(b) The derivative of A_total with respect to x is ...

  dA/dx = x/8 -(L-x)/(6√3)

This will be zero when ...

  x/8 = (L-x)/(6√3)

  x(6√3) = 8L -8x

  x(8 +6√3) = 8L

  x = L·8/(6√3 +8) = 8L(6√3 -8)/(64-108)

  x = L·(12√3 -16)/11

The total area is minimized when L·(12√3 -16)/11 is devoted to the square, and the balance is devoted to the triangle.

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This problem uses the teengamb data set in the faraway package. Fit a model with gamble as the response and the other variables
hichkok12 [17]

Answer:

A. 95% confidence interval of gamble amount is (18.78277, 37.70227)

B. The 95% confidence interval of gamble amount is (42.23237, 100.3835)

C. 95% confidence interval of sqrt(gamble) is (3.180676, 4.918371)

D. The predicted bet value for a woman with status = 20, income = 1, verbal = 10, which shows a negative result and does not fit with the data, so it is inferred that model (c) does not fit with this information

Step-by-step explanation:

to)

We will see a code with which it can be predicted that an average man with income and verbal score maintains an appropriate 95% CI.

attach (teengamb)

model = lm (bet ~ sex + status + income + verbal)

newdata = data.frame (sex = 0, state = mean (state), income = mean (income), verbal = mean (verbal))

predict (model, new data, interval = "predict")

lwr upr setting

28.24252 -18.51536 75.00039

we can deduce that an average man, with income and verbal score can play 28.24252 times

using the following formula you can obtain the confidence interval for the bet amount of 95%

predict (model, new data, range = "confidence")

lwr upr setting

28.24252 18.78277 37.70227

as a result, the confidence interval of 95% of the bet amount is (18.78277, 37.70227)

b)

Run the following command to predict a man with maximum values ​​for status, income, and verbal score.

newdata1 = data.frame (sex = 0, state = max (state), income = max (income), verbal = max (verbal))

predict (model, new data1, interval = "confidence")

lwr upr setting

71.30794 42.23237 100.3835

we can deduce that a man with the maximum state, income and verbal punctuation is going to bet 71.30794

The 95% confidence interval of the bet amount is (42.23237, 100.3835)

it is observed that the confidence interval is wider for a man in maximum state than for an average man, it is an expected data because the bet value will be higher than the person with maximum state that the average what you carried s that simultaneously The, the standard error and the width of the confidence interval is wider for maximum data values.

(C)

Run the following code for the new model and predict the answer.

model1 = lm (sqrt (bet) ~ sex + status + income + verbal)

we replace:

predict (model1, new data, range = "confidence")

lwr upr setting

4,049523 3,180676 4.918371

The predicted sqrt (bet) is 4.049523. which is equal to the bet amount is 16.39864.

The 95% confidence interval of sqrt (wager) is (3.180676, 4.918371)

(d)

We will see the code to predict women with status = 20, income = 1, verbal = 10.

newdata2 = data.frame (sex = 1, state = 20, income = 1, verbal = 10)

predict (model1, new data2, interval = "confidence")

lwr upr setting

-2.08648 -4.445937 0.272978

The predicted bet value for a woman with status = 20, income = 1, verbal = 10, which shows a negative result and does not fit with the data, so it is inferred that model (c) does not fit with this information

4 0
3 years ago
The perimeter of a triangle is 45 centimeters. find the lengths of its sides if the longest side is 7 centimeters longer than th
dangina [55]
X = length of shortest side
Therefore the remaining sides will be x +2 and x + 7

x + x + 2 + x +7 = 45
3x + 9 = 45
3x = 36
x = 12
x + 2 = 14
x + 7 = 19

The sides are 12, 14, and 19 cm. long. Hope this helped!
3 0
3 years ago
Katrice wrote the numbers 137 and 174. Which sentence is true about the digit 7 in each number?
marshall27 [118]

Answer:

The 7 in 137 represents ten times the 7 in 137 (the second option)

Step-by-step explanation:

The seven in 137 equals 7

The seven in 174 equals 70

7 times 10 = 70

I hope this helped!

5 0
3 years ago
Kai has begun to list, in ascending order, the positive integers which are not factors of
Keith_Richards [23]

Answer:17

7, 9, 11, 13, 14, 17,

6 0
3 years ago
A rectangle has an area of 105 square feet. If the sum of the length and the width is 26 feet, find the dimensions. Include unit
Andrei [34K]

L x W = 105

L + W = 26 so L = 26 - W

substitute L = 26 - W into L x W = 105


(26 - W) x W = 105

26W - W^2 = 105

W^2 - 26W + 105 = 0

(W - 21)(W - 5) = 0

W - 21 = 0; W = 21

W - 5 = 0; W = 5


The the dimensions of the rectangle are 5 ft and 21 ft.


Double check:

The sum of the length and the width is 26 feet: 21 + 5 = 26 feet

A rectangle has an area of 105 square feet: 21 x 5 = 105 square feet



8 0
3 years ago
Read 2 more answers
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