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Tju [1.3M]
2 years ago
11

A firecracker shoots up from a hill 160 feet high, with an initial speed of 90 feet per second. Using the formula H(t) = −16t2 +

vt + s, approximately how long will it take the firecracker to hit the ground?
A. Five seconds
B. Six seconds
C.Seven seconds
D.Eight seconds
Mathematics
1 answer:
Katarina [22]2 years ago
3 0

H(t) = -16t² + vt + s

Where -16 is half of the gravitational constant of almost 32 ft/sec (downward, thus negative),

v is the initial velocity (90), and

s is the starting height (160)

so we have:

H(t) = -16t² + 90t + 160

How long before it hits the ground? Solve for h(t) = 0:

0 = -16t² + 90t + 160

Divide both sides by -2:

0 = 8t² - 45t - 80

Quadratic equation:

t = [ -b ± √(b² - 4ac)] / (2a)

t = [ -(-45) ± √((-45)² - 4(8)(-80))] / (2(8))

t = [ 45 ± √(2025 + 2560)] / 16

t = [ 45 ± √(4585)] / 16

throwing out the negative time:

t = (45 + √4585) / 16

t ≈ 7.04 seconds

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Answer:

Perimeter = 18.7 units

Area = 13.5 units²

Step-by-step explanation:

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Length of AD = 3 units

By applying Pythagoras theorem in ΔDBE,

DE² = DB² + BE²

DE² = 3² + 3²

DE = √18

DE = 4.24 units

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By applying Pythagoras theorem in ΔABC,

AC² = AB² + BC²

AC² = 6² + 6²

AC = √72

AC = 8.49 units

Perimeter of ADEC = 3 + 4.24 + 3 + 8.49

                                 = 18.73 units

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Area of ADEC = Area of ΔABC - Area of ΔBDE

Area of ΔABC = \frac{1}{2}(AB)(BC)

                       = \frac{1}{2}(6)(6)

                       = 18 units²

Area of ΔBDE = \frac{1}{2}(BD)(BE)

                       = \frac{1}{2}(3)(3)

                       = 4.5 units²

Area of ADEC = 18 - 4.5

                        = 13.5 units²

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3 years ago
Rationalize the denominator.
AlekseyPX

Hello and Good Morning/Afternoon!

<u>Let's take this problem step-by-step</u>:

<u>What the problem asks for:</u>

  ⇒ to rationalize the denominator

      ⇒ rationalize means that you multiply the numerator and

          demonimator by the denominator

<u>Let's put that into action</u>:

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<u></u>

Hopefully that helps!

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Her is your answer 3% of the sales is $180

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