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3 years ago

I need help asap:

Mathematics

1 answer:

lisov135 [29]3 years ago

5 0

Answer:

79.4° to the nearest tenth of a degree

Step-by-step explanation:

You are trying to find the angle opposite the side of length 27.

Let the length of that side be c and a and b be the lengths of the other two sides and let C be the measure of the angle you are looking for

Using the law of cosines

$c = \sqrt{a^{2} + b^{2} - 2abcos C}$

$27 = \sqrt{19^{2} + 23^{2} - 2(19)(23)cosC}$

$27^{2} = 19^{2} + 23^{2} - 2(19)(23)cosC$

729 = 361 + 529 - 874cosC

729 = 890 - 874cosC

-161 = -874cosC

-161/-874 = cosC

.1842105.... = cosC

C = arccos .1842105.... = 79.4° to the nearest tenth of a degree

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The system of equations may have a unique solution, an infinite number of solutions, or no solution. Use matrices to find the ge

Leno4ka [110]

Answer:

Infinite number of solutions.

Step-by-step explanation:

We are given system of equations

$5x+4y+5z=-1$

$x+y+2z=1$

$2x+y-z=-3$

Firs we find determinant of system of equations

Let a matrix A= $\left[\begin{array}{ccc}5&4&5\\1&1&2\\2&1&-1\end{array}\right]$ and B= $\left[\begin{array}{ccc}-1\\1\\-3\end{array}\right]$

$\mid A\mid=\begin{vmatrix}5&4&5\\1&1&2\\2&1&-1\end{vmatrix}$

$\mid A\mid=5(-1-2)-4(-1-4)+5(1-2)=-15+20-5=0$

Determinant of given system of equation is zero therefore, the general solution of system of equation is many solution or no solution.

We are finding rank of matrix

Apply $R_1\rightarrow R_1-4R_2$ and $R_3\rightarrow R_3-2R_2$

$\left[\begin{array}{ccc}1&0&1\\1&1&2\\0&-1&-3\end{array}\right]$ : $\left[\begin{array}{ccc}-5\\1\\-5\end{array}\right]$

Apply $R_2\rightarrow R_2-R_1$

$\left[\begin{array}{ccc}1&0&1\\0&1&1\\0&-1&-3\end{array}\right]$ : $\left[\begin{array}{ccc}-5\\6\\-5\end{array}\right]$

Apply $R_3\rightarrow R_3+R_2$

$\left[\begin{array}{ccc}1&0&1\\0&1&1\\0&0&-2\end{array}\right]$ : $\left[\begin{array}{ccc}-5\\6\\1\end{array}\right]$

Apply $R_3\rightarrow- \frac{1}{2}$ and $R_2\rightarrow R_2-R_3$

$\left[\begin{array}{ccc}1&0&1\\0&1&0\\0&0&1\end{array}\right]$ : $\left[\begin{array}{ccc}-5\\\frac{13}{2}\\-\frac{1}{2}\end{array}\right]$

Apply $R_1\rightarrow R_1-R_3$

$\left[\begin{array}{ccc}1&0&0\\0&1&0\\0&0&1\end{array}\right]$ : $\left[\begin{array}{ccc}-\frac{9}{2}\\\frac{13}{2}\\-\frac{1}{2}\end{array}\right]$

Rank of matrix A and B are equal.Therefore, matrix A has infinite number of solutions.

Therefore, rank of matrix is equal to rank of B.

4 0

3 years ago

Jessica needs to make a necklace for 3 of her friends, including her. she wants to use 4.5 inches of string for each necklace. s

hoa [83]

Answer:

She can make two necklaces with 10 inches. 8 more inches

Step-by-step explanation:

5 0

3 years ago

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A truck left a station at 6:00am traveling at a rate of 45km/h. A van left the same place 2 hours later heading in the same dire

OverLord2011 [107]

The Van would catch up with the truck at 6:00 pm

Speed is the ratio of distance travelled to time taken. It is given by:

Speed = distance / time

Let us say the van catch up with the truck after t hours at a distance d.

For the truck:

45 = d/t

d = 45t

For the Van:

54 = d / (t - 2)

d = 54t - 108

45t = 54t - 108

9t = 108

t = 12 hours

The Van would catch up with the truck at 6:00 pm

Find out more on speed at: brainly.com/question/3004254

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2 years ago

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Find the value of x.

castortr0y [4]

The angle x has a measure of 110 degrees

<h3>How to determine the value of x?</h3>

From the question, we have the triangle shape that can be used in our computation:

On the triangle, the external angles are

x, 140 and 110

These angles are on the same straight line with their corresponding internal angles

By the angle on a straight line theorem, we have the internal angles to be

180 - x, 180 - 140 and 180 - 110

The sum of these angles is 180

So, we have

180 - x + 180 - 140 + 180 - 110 = 180

Evaluate

x = 110

Hence, the value of x is 110 degrees