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Tara standing 20 feet from a tree and the angle of elevation is 72°. About how tall is the tree?

Zinaida [17]

Answer:

Approx 61.554 feet

Step-by-step explanation:

Since we are dealing with the opposite and adjacent sides, we will use tangent as our ratio.

Since the angle of elevation is 72 degrees, the left side of our equation is $tan(72)$ .

The right side of the equation is opposite over adjacent.

$x/20$

Set these equal to each other.

$tan(72) = x/20$

Simplify.

$20 tan(72)=x$

$20(3.078) = x$

x is approximately 61.554.

4 0

3 years ago

Lagrange multipliers have a definite meaning in load balancing for electric network problems. Consider the generators that can o

Ivahew [28]

Answer:

The load balance $(x_1,x_2,x_3)=(545.5,272.7,181.8)$ Mw minimizes the total cost

Step-by-step explanation:

<u>Optimizing With Lagrange Multipliers</u>

When a multivariable function f is to be maximized or minimized, the Lagrange multipliers method is a pretty common and easy tool to apply when the restrictions are in the form of equalities.

Consider three generators that can output xi megawatts, with i ranging from 1 to 3. The set of unknown variables is x1, x2, x3.

The cost of each generator is given by the formula

$\displaystyle C_i=3x_i+\frac{i}{40}x_i^2$

It means the cost for each generator is expanded as

$\displaystyle C_1=3x_1+\frac{1}{40}x_1^2$

$\displaystyle C_2=3x_2+\frac{2}{40}x_2^2$

$\displaystyle C_3=3x_3+\frac{3}{40}x_3^2$

The total cost of production is

$\displaystyle C(x_1,x_2,x_3)=3x_1+\frac{1}{40}x_1^2+3x_2+\frac{2}{40}x_2^2+3x_3+\frac{3}{40}x_3^2$

Simplifying and rearranging, we have the objective function to minimize:

$\displaystyle C(x_1,x_2,x_3)=3(x_1+x_2+x_3)+\frac{1}{40}(x_1^2+2x_2^2+3x_3^2)$

The restriction can be modeled as a function g(x)=0:

$g: x_1+x_2+x_3=1000$

Or

$g(x_1,x_2,x_3)= x_1+x_2+x_3-1000$

We now construct the auxiliary function

$f(x_1,x_2,x_3)=C(x_1,x_2,x_3)-\lambda g(x_1,x_2,x_3)$

$\displaystyle f(x_1,x_2,x_3)=3(x_1+x_2+x_3)+\frac{1}{40}(x_1^2+2x_2^2+3x_3^2)-\lambda (x_1+x_2+x_3-1000)$

We find all the partial derivatives of f and equate them to 0

$\displaystyle f_{x1}=3+\frac{2}{40}x_1-\lambda=0$

$\displaystyle f_{x2}=3+\frac{4}{40}x_2-\lambda=0$

$\displaystyle f_{x3}=3+\frac{6}{40}x_3-\lambda=0$

$f_\lambda=x_1+x_2+x_3-1000=0$

Solving for \lambda in the three first equations, we have

$\displaystyle \lambda=3+\frac{2}{40}x_1$

$\displaystyle \lambda=3+\frac{4}{40}x_2$

$\displaystyle \lambda=3+\frac{6}{40}x_3$

Equating them, we find:

$x_1=3x_3$

$\displaystyle x_2=\frac{3}{2}x_3$

Replacing into the restriction (or the fourth derivative)

$x_1+x_2+x_3-1000=0$

$\displaystyle 3x_3+\frac{3}{2}x_3+x_3-1000=0$

$\displaystyle \frac{11}{2}x_3=1000$

$x_3=181.8\ MW$

And also

$x_1=545.5\ MW$

$x_2=272.7\ MW$

The load balance $(x_1,x_2,x_3)=(545.5,272.7,181.8)$ Mw minimizes the total cost

5 0

4 years ago

The surface area of the pyramid with square base that measures 8 ft by 8 ft and slant height of 12 ft is 256 ft^2.

Maru [420]

Eeeeeeertyuiopppppppppppppppppppppppppp

5 0

3 years ago

Which of the following is a true statement? a) The correlation coefficient r is always greater than 1. b) The coefficient of det

brilliants [131]

Answer:

f) None of the above.

Step-by-step explanation:

When we try to adjust a curve from a scatter plot to try and predict values of the dependent variable y given known values of the independent variable x.

The curve is a function y=f(x) which usually is a line, a logarithmic, parabola, power or exponential.

In order to choose which curve adjust the best, we compute a number r called correlation coefficient.

The closer r is to -1 or +1, the better the curve adjust the scatter plot.

When r =0, we say there is no correlation between the points x and y

When -1<r<0 we say there is a negative correlation, this means that the values of y decrease as the values of x increase.

When 0<r<1 we say there is a positive correlation, this means that the values of y increase as the values of x increase.

When r =1 or r =-1, we say that there is a perfect correlation. It means that all of the points of the scatter plot lie on the curve.

So, from the possible choices of answer, f) None of the above is the right one.

6 0

3 years ago

What inequality is represented by the graph?

lyudmila [28]

Answer:

Step-by-step explanation:

i can not see the pic

6 0

4 years ago