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DENIUS [597]
3 years ago
10

How many points are needed to define a ray? 0 1 2 3

Mathematics
2 answers:
beks73 [17]3 years ago
5 0
You only need 1 point to define a ray
Rzqust [24]3 years ago
5 0
You only need one. It can be written as two ways.
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A cable television compan is laying cable in an area with underground utilities. Two subdivisions are located on opposite sides
Schach [20]

Answer:

Step-by-step explanation:

Given:

Point Q = Q is on the north bank 1200 m east of P $40/m to lay cable underground and $80/m way to lay the cable.

Lets denote T be a point on north bank, therefore, point T is t m east and 100m north of P.

Note that 0 < t < 1200

Distance from P to T using Pythagoras theorem:

PT^2 = PQ^2 + QT^2

PT = √(t²+100²) = √(t²+10,000)

Distance from T to Q:

TQ = 1200 - t

From above, Cable from P to T is underwater, and costs $80/m to lay.

Cable from T to Q is underground, and costs $40/m to lay.

Total cost of the cable:

C(t) = 80√(t²+10,000) + 40(1200 - t)

Cost is at its minimum: when dC/dt = C'(t) = 0 and d^2C/dt^2 = C''(t) > 0

dC/dt = C'(t)

= 80 * 1/2 (t² + 10,000)^(-1/2) × 2t + 40 × (-1)

dC/dt = C'(t)

= 80t/√(t² + 10,000) - 40 = 0

80t/√(t² + 10,000) = 40

80t = 40√(t² + 10,000)

2t = √(t² + 10,000)

square both sides:

4t² = t² + 10,000

3t² = 10,000

t² = 10,000/3

t = 100/√3

≈ 57.735

d^2C/dt^2 =

C''(t) = [80√(t² + 10,000) - 80t × t/√(t²+10,000)] /√(t²+10,000)

C''(t) = [(80(t²+10,000) - 80t²) / √(t²+10,000)] /√(t²+10,000)

C''(t) = 800,000 / (t² + 10,000)^(3/2)

C''(t) > 0 for all t

Therefore C(t) is minimized at t = 100/√3

C(100/√3) = 80√(10,000/3 + 10,000) + 40 × (1200 - 100/√3)

= 80 √(40,000/3) + 48,000 - 4000/√3

= 16000/√3 + 48,000 - 4000/√3

= 48,000 + 12,000/√3

= 48,000 + 4,000√3

= 4000 (12 + √3)

≈ 54,928.20

Minimum cost is $54,928.20

This occurs when cable is laid underwater from point P to point T(57.735 m east and 100m north of P) and then underground from point T to point Q (1200 - 57.735)

= 1142.265 m

5 0
3 years ago
Find the area of the circle to the nearest tenth.<br> 8 cm
liraira [26]

Answer:

201.06.................

4 0
3 years ago
Since 2010, when 102390 Cases were reported, each year the number of new flu cases decrease to 85% of the prior year. Predict th
BaLLatris [955]

Answer:

20,158 cases

Step-by-step explanation:

Let t=0 represent year 2010.

We have been given that since 2010, when 102390 Cases were reported, each year the number of new flu cases decrease to 85% of the prior year.

Since the flu cases decrease to 85% of the prior year, so the flu cases for every next year will be 85% of last year and decay rate is 15%.

We can represent this information in an exponential decay function as:

F(t)=102,390(1-0.15)^t

F(t)=102,390(0.85)^t

To find number of cases in 2020, we will substitute t=10 in our decay function as:

F(10)=102,390(0.85)^{10}

F(10)=102,390(0.1968744043407227)

F(10)=20,157.970260446597\approx 20,158

Therefore, 20,158 cases  will be reported in 2020.

3 0
3 years ago
Use the substitution method to solve the system of equations
Sergeeva-Olga [200]

Answer:

x=1/4

y = -2

(1/4, -2)

b

Step-by-step explanation:

4x -y =3

y =-8x

substitute y =-8x into the first equation.  Everywhere you see y put 8x

4x -y =3

4x - (-8x) =3

4x+8x=3

combine like terms

12x = 3

divide by 12

12x/12x = 3 /12

x = 1/4

now we need to find y

y = -8x

y = -8 * 1/4

y = -2

8 0
3 years ago
Please help me answer these questions if you give an answer you are a lifesaver
il63 [147K]
On Part A you have to subtract $2.39-$1.99. Then in Part B you have to multiply $4.50 by 2. And then I think you have to add $3.79 when u are done multiplying.
4 0
2 years ago
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