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2 years ago

Please just give me the number answer no equation

Mathematics

1 answer:

joja [24]2 years ago

8 0

13 cm

Explanation:-

I'm not so sure, but I hope this is the answer.

Given, SR=39cm

To find WX

As WX is parallel to Sr, WX is half of SR

$→ WX = \frac{39}{2}$

$→WX = 13cm$

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You are a lifeguard and spot a drowning child 60 meters along the shore and 40 meters from the shore to the child. You run along

sukhopar [10]

Answer:

The lifeguard should run across the shore a distance of 48.074 m before jumpng into the water in order to minimize the time to reach the child.

Step-by-step explanation:

This is a problem of optimization.

We have to minimize the time it takes for the lifeguard to reach the child.

The time can be calculated by dividing the distance by the speed for each section.

The distance in the shore and in the water depends on when the lifeguard gets in the water. We use the variable x to model this, as seen in the picture attached.

Then, the distance in the shore is d_b=x and the distance swimming can be calculated using the Pithagorean theorem:

$d_s^2=(60-x)^2+40^2=60^2-120x+x^2+40^2=x^2-120x+5200\\\\d_s=\sqrt{x^2-120x+5200}$

Then, the time (speed divided by distance) is:

$t=d_b/v_b+d_s/v_s\\\\t=x/4+\sqrt{x^2-120x+5200}/1.1$

To optimize this function we have to derive and equal to zero:

$\dfrac{dt}{dx}=\dfrac{1}{4}+\dfrac{1}{1.1}(\dfrac{1}{2})\dfrac{2x-120}{\sqrt{x^2-120x+5200}} \\\\\\\dfrac{dt}{dx}=\dfrac{1}{4} +\dfrac{1}{1.1} \dfrac{x-60}{\sqrt{x^2-120x+5200}} =0\\\\\\ \dfrac{x-60}{\sqrt{x^2-120x+5200}} =\dfrac{1.1}{4}=\dfrac{2}{7}\\\\\\ x-60=\dfrac{2}{7}\sqrt{x^2-120x+5200}\\\\\\(x-60)^2=\dfrac{2^2}{7^2}(x^2-120x+5200)\\\\\\(x-60)^2=\dfrac{4}{49}[(x-60)^2+40^2]\\\\\\(1-4/49)(x-60)^2=4*40^2/49=6400/49\\\\(45/49)(x-60)^2=6400/49\\\\45(x-60)^2=6400\\\\$

$x$

As $d_b=x$ , the lifeguard should run across the shore a distance of 48.074 m before jumpng into the water in order to minimize the time to reach the child.

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3 years ago

the width of a rectangle is 1 units less than the length. the area of the rectangle is 56 units. what is the width, in units, of

Oksana_A [137]

Answer: Length = 8 units, Width = 7 units

8 0

3 years ago

BRAINLEST AND POINTS IF CORRECT

Natasha2012 [34]

Answer:

a. −1973700x

b. 0.12

c. 1344

d. − 36.2

Step-by-step explanation:

6 0

2 years ago

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A group of farmers planted 62 fields of vegetables. of the fields they planted, 4/5 were planted with cabbage. how many fields o

chubhunter [2.5K]

Total number of fields of vegetables = 62

Thus,

The amount of fields that is cabbage = $\frac{4}{5} * 62 = \frac{248 }{5} = 49.8$

4 0

3 years ago

D is partly constant and partly varies with V. When V = 40, D = 150, and when V = 54, D = 192. Find D when V = 73.

Temka [501]

D = mV + C , ( compare this to your familiar y = mx + b)
when V=40, D=150
150 = 40m + C **
when V=54, D=192
192 = 54m + C ***
subtract ** from ***
42 = 14m
m = 3
sub into ** , 150 = 120 + C
C = 30

so you have D = 3V + 30

sub in your given value of V

8 0

3 years ago