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3 years ago

In the diagram below of triangle PQR, S is the midpoint of PR and T is the

Mathematics

1 answer:

Nina [5.8K]3 years ago

5 0

Answer:

ST = 4

Step-by-step explanation:

A segment joining the midpoints of 2 sides of a triangle is half the length of the third side.

ST = $\frac{1}{2}$ PQ substitute values

- 32 + 9x = $\frac{1}{2}$ (- 5x + 28) ← multiply both sides by 2 to clear the fraction

- 64 + 18x = - 5x + 28 (add 5x to both sides )

- 64 + 23x = 28 ( add 64 to both sides )

23x = 92 ( divide both sides by 23 )

x = 4

Then

ST = - 32 + 9x = - 32 + 9(4) = - 32 + 36 = 4

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A cylinder shaped can needs to be constructed to hold 500 cubic centimeters of soup. The material for the sides of the can costs

iogann1982 [59]

Answer:

r=3.628cm

h=12.093cm

Step-by-step explanation:

For this problem we are going to use principles, concepts and calculations from multivariable calculus; mainly we are going to use the Lagrange multipliers method. This method is thought to help us to find a extreme value of a multivariable function 'F' given a restriction 'G'. F represents the function that we want to optimize and G is just a relation between the variables of which F depends. The Lagrange method for just one restriction is:

$\nabla F=\lambda \nabla G$

First, let's build the function that we want to optimize, that is the cost. The cost is a function that must sum the cost of the sides material and the cost of the top and bottom material. The cost of the sides material is the unitary cost (0.03) multiplied by the sides area, which is $A_s=2\pi rh$ for a cylinder; while the cost of the top and bottom material is the unitary cost (0.05) multiplied by the area of this faces, which is $A_{TyB}=2\pi r^2$ for a cylinder.

So, the cost function 'C' is:

$C=2\pi rh*0.03+2\pi r^2*0.05\\C=0.06\pi rh+0.1\pi r^2$

The restriction is the volume, which has to be of 500 cubic centimeters:

$V=500=\pi r^2h\\500=\pi hr^2$

So, let's apply the Lagrange multiplier method:

$\nabla C=\lambda \nabla V\\\frac{\partial C}{\partial r}=0.06\pi h+0.2\pi r\\\frac{\partial C}{\partial h}=0.06\pi r\\\frac{\partial V}{\partial r}=2\pi rh\\\frac{\partial V}{\partial h}=\pi r^2\\(0.06\pi h+0.2\pi r,0.06\pi r)=\lambda (2\pi rh,\pi r^2)$

At this point we have a three variable (h,r, λ)-three equation system, which solution will be the optimum point for the cost (the minimum). Let's write the system:

$0.06\pi h+0.2\pi r=2\lambda \pi rh\\0.06\pi r=\lambda \pi r^2\\500=\pi hr^2$

(In this kind of problems always the additional equation is the restricion, in this case, V=500).

Let's divide the first and second equations by π:

$0.06h+0.2r=2\lambda rh\\0.06r=\lambda r^2\\500=\pi hr^2$

Isolate λ from the second equation:

$\lambda =\frac{0.06}{r}$

Isolate h from the third equation:

$h=\frac{500}{\pi r^2}$

And then, replace λ and h in the first equation:

$0.06*\frac{500}{\pi r^2} +0.2r=2*(\frac{0.06}{r})r\frac{500}{\pi r^2} \\\frac{30}{\pi r^2}+0.2r= \frac{60}{\pi r^2}$

Multiply all the resultant equation by $\pi r^{2}$ :

$30+0.2\pi r^3=60\\0.2\pi r^3=30\\r^3=\frac{30}{0.2\pi } =\frac{150}{\pi}\\r=\sqrt[3]{\frac{150}{\pi}}\approx 3.628cm$

Then, find h by the equation $h=\frac{500}{\pi r^2}$ founded above:

$h=\frac{500}{\pi r^2}\\h=\frac{500}{\pi (3.628)^2}=12.093cm$

4 0

3 years ago

The Dewey Civic Center has 1,600 seats. Tickets for 85% of the total number of seats were sold. How many tickets were sold?

Juliette [100K]

1600×85%=1360 I think that 1360 Tickets were sold

4 0

3 years ago

Find the values of x and y if 5 ˣ⁻³ x 3²ʸ⁻⁸ =225

-BARSIC- [3]

Answer:

x = 5, y = 5

Step-by-step explanation:

${5}^{x - 3} \times {3}^{2y - 8} = 225 \\ {5}^{x - 3} \times {3}^{2y - 8} = 25 \times 9 \\ {5}^{x - 3} \times {3}^{2y - 8} = {5}^{2} \times {3}^{2} \\ equating \: like \: power \: terms \: from \: both \:\\ sides \\ {5}^{x - 3} = {5}^{2} \\ x - 3 = 2 (Bases\: are\: equal, \: so\: exponents \: \\will\: also\: be\: equal) \\ x = 3 + 2 \\ \huge \red{ \boxed{ x = 5}} \\ \\ {3}^{2y - 8} = {3}^{2} \\ 2y - 8 = 2(Bases\: are\: equal, \: so\: exponents \: \\will\: also\: be\: equal) \\ 2y = 2 + 8 \\ 2y = 10 \\ y = \frac{10}{2} \\ \huge \purple{ \boxed{y = 5}}$

5 0

3 years ago

Type the correct answer in each box. Use numerals instead of words.

stira [4]

The system of equations when been placed in a matrix yields

$\left[\begin{array}{ccc}650&-1\\120&1\end{array}\right]\left[\begin{array}{ccc}x\\y\end{array}\right] =\left[\begin{array}{ccc}-175\\25080\end{array}\right]$

<h3>What is an equation?</h3>

An equation is an expression that shows the relationship between two or more variables and numbers.

Given the equation:

y = 650x + 175 and;

y = 25080 - 120x

Rearranging the equations gives:

650x - y = -175 and;

120x + y = 25080

Placing the equations in a matrix gives:

$\left[\begin{array}{ccc}650&-1\\120&1\end{array}\right]\left[\begin{array}{ccc}x\\y\end{array}\right] =\left[\begin{array}{ccc}-175\\25080\end{array}\right]$

The system of equations when been placed in a matrix yields

$\left[\begin{array}{ccc}650&-1\\120&1\end{array}\right]\left[\begin{array}{ccc}x\\y\end{array}\right] =\left[\begin{array}{ccc}-175\\25080\end{array}\right]$

Find out more on equation at: brainly.com/question/2972832

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6 0

2 years ago

Nathan had an infection, and his doctor wanted him to take penicillin. Because Nathan’s father and paternal grandfather were all

Art [367]

Nathan has an infection and he needs to be treated with penicillin
But there’s a 75% probability of him being allergic to penicillin
And to test if the skin reacts to penicillin, the test is 98% accuracy
So even if he has the allergy the test is only 98% accurate of identifying the allergy
Therefore we are asked to find the probability of both these events happening
Event 1 and event 2 both should happen then. When the ‘and’ function is used in probabilities then the probabilities of both events happening should be multiplied
Therefore probability that Nathan has the allergy and test predicts it is
= 75% x 98% = 0.735
The answer is D. 0.735

6 0

3 years ago