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nataly862011 [7]
3 years ago
12

A street light is mounted at the top of a 15-ft-tall pole. A man 6 ft tall walks away from the pole with a speed of 7 ft/s along

a straight path. How fast is the tip of his shadow moving when he is 30 ft from the pole?

Mathematics
2 answers:
saul85 [17]3 years ago
7 0

Answer:

Since only his speed affects how fast his shadow moves, then we calculate for the speed which is 11.67ft/s

Step-by-step explanation:

Assuming similar triangle

(y-x)/y = 6/15

15(y-x) = 6y

15y - 15x = 6y

(15 -6)y = 15x

9y = 15x

y = (5/3)x

By differentiating both sides with respect to time t

dy/dt = 5/3 (dx/dt)

But (dx/dt) is 7 ft/s

Therefore dy/dt = 5/3 * 7 = 35/3 = 11.67ft/s

djverab [1.8K]3 years ago
6 0

Answer:

Step-by-step explanation:

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A software designer is mapping the streets for a new racing game. all of the streets are depicted as either perpendicular or par
ElenaW [278]

The equation of the central street PQ is  -1.5x - 3.5y = -31.5 option (b) is correct.

<h3>What is a straight line?</h3>

A straight line is a combination of endless points joined on both sides of the point.

We have a straight line:

-7x+3y=-21.5  

Convert it to the general form given below:

\rm y=mx+c

\rm 3y=-21.5+7x\\\\ \rm y = \frac{-21.5}{3}+\frac{7}{3}x or

\rm y = \frac{7}{3}x-\frac{21.5}{3}

m = \frac{7}{3}   (Slope of AB line)

For the slope(m') of the PQ line:

\rm m'=-\frac{1}{m}    ( because AB and PQ are perpendicular to each other)

\rm m' = -\frac{3}{7}

We know the:

\rm (y-y')=m'(x-x')

Where (x', y') = (7, 6), we get:

\rm (y-6)=-\frac{3}{7} (x-7)

\rm 7(y-6)=-3 (x-7)\\\\\rm 7y-42= -3x+21\\\\\rm 7y= -3x+21+42\\\\\rm 3x+7y=63

\rm -1.5x-3.5y=-31.5   (multiply by -1/2 on both sides)

Thus, the equation of the central street PQ is  -1.5x - 3.5y = -31.5

Learn more about the straight line.

brainly.com/question/3493733

6 0
2 years ago
A train traveled 1360 miles in 16 hours. What was the average speed of the train in miles per hour?
notsponge [240]

Answer:

85 miles per hour

Step-by-step explanation:

5 0
3 years ago
How many trucks carried only late variety?
murzikaleks [220]

9514 1404 393

Answer:

  • late only: 15
  • extra-late only: 24
  • one type: 43
  • total trucks: 105

Step-by-step explanation:

It works well when making a Venn diagram to start in the middle (6 carried all three), then work out.

For example, if 10 carried early and extra-late, then only 10-6 = 4 of those trucks carried just early and extra-late.

Similarly, if 30 carried early and late, and 4 more carried only early and extra-late, then 38-30-4 = 4 carried only early. In the attached, the "only" numbers for a single type are circled, to differentiate them from the "total" numbers for that type.

__

a) 15 trucks carried only late

b) 24 trucks carried only extra late

c) 4+15+24 = 43 trucks carried only one type

d) 38+67+56 -30-28-10 +6 +6 = 105 trucks in all went out

8 0
3 years ago
Multiply the polynomials. (x – 5)(x2 + 4x – 2)
klemol [59]

the cheap answer is simply

(x-5)(x²+4x-2)

we can simply multiply the terms on one by the terms of the other and then add like-terms and simplify.

\bf (x-5)(x^2+4x-2)\implies \begin{array}{cllll} x^2+4x-2\\ \times x\\ \cline{1-1}\\ x^3+4x^2-2x \end{array}+ \begin{array}{cllll} x^2+4x-2\\ \times -5\\ \cline{1-1}\\ -5x^2-20x+10 \end{array} \\\\\\ x^3+4x^2-2x-5x^2-20x+10\implies x^3+4x^2-5x^2-2x-20x+10 \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ ~\hfill x^3-x^2-22x+10~\hfill

6 0
3 years ago
Read 2 more answers
You want to purchase a new car in 55
Tanzania [10]

Answer:

Ans. you should deposit each month to end up with $38,000 the amount of $533.33 every month for 5 years at a APR of 6.5%

Step-by-step explanation:

Hi, first we have to convert all the data to monthly basis, that is, 5 years (5*12=60 months) and the rate of 6.5% APR offered by the bank (Monthly rate = 0.065/12=0,005666667  or 0.5667% monthly)

With that in mind, we need to solve for "A" the following equation.

FV=\frac{A((1+r)^{n}-1) }{r}

Where:

FV = Future value of the car

r = rate of return offered by the bank

n = number of periods that you are going to make the monthly deposit

That is:

38,000=\frac{A((1+0,005667)^{60}-1) }{0,005667}

38,000=\frac{A(0,403599896)}{0,005667}

38,000=A(71,22351103)

A= 533,53

Best of luck.

5 0
3 years ago
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