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baherus [9]
3 years ago
11

A combination of 3 erasers and 5 pencils cost $7.55. A combination of 6 erasers and 12 pencils cost $17.40. How much is each pen

cil?
Mathematics
1 answer:
Murljashka [212]3 years ago
3 0

Answer:

9.85

Step-by-step explanation:

I subtract 17.40 and 7.55 to get 9.85 they just wanted to know how much the pencil cost not erasers.

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It c) because it 56 out of 100
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6. Two observers, 7220 feet apart, observe a balloonist flying overhead between them. Their measures of the
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Answer:

The ballonist is at a height of 3579.91 ft above the ground at 3:30pm.

Step-by-step explanation:

Let's call:

h the height of the ballonist above the ground,

a the distance between the two observers,

a_1 the horizontal distance between the first observer and the ballonist

a_2 the horizontal distance between the second observer and the ballonist

\alpha _1 and \alpha _2 the angles of elevation meassured by each observer

S the area of the triangle formed with the observers and the ballonist

So, the area of a triangle is the length of its base times its height.

S=a*h (equation 1)

but we can divide the triangle in two right triangles using the height line. So the total area will be equal to the addition of each individual area.

S=S_1+S_2 (equation 2)

S_1=a_1*h

But we can write S_1 in terms of \alpha _1, like this:

\tan(\alpha _1)=\frac{h}{a_1} \\a_1=\frac{h}{\tan(\alpha _1)} \\S_1=\frac{h^{2} }{\tan(\alpha _1)}

And for S_2 will be the same:

S_2=\frac{h^{2} }{\tan(\alpha _2)}

Replacing in the equation 2:

S=\frac{h^{2} }{\tan(\alpha _1)}+\frac{h^{2} }{\tan(\alpha _2)}\\S=h^{2}*(\frac{1 }{\tan(\alpha _1)}+\frac{1}{\tan(\alpha _2)})

And replacing in the equation 1:

h^{2}*(\frac{1 }{\tan(\alpha _1)}+\frac{1}{\tan(\alpha _2)})=a*h\\h=\frac{a}{(\frac{1 }{\tan(\alpha _1)}+\frac{1}{\tan(\alpha _2)})}

So, we can replace all the known data in the last equation:

h=\frac{a}{(\frac{1 }{\tan(\alpha _1)}+\frac{1}{\tan(\alpha _2)})}\\h=\frac{7220 ft}{(\frac{1 }{\tan(35.6)}+\frac{1}{\tan(58.2)})}\\h=3579,91 ft

Then, the ballonist is at a height of 3579.91 ft above the ground at 3:30pm.

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Step-by-step explanation:

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If √(0.09×0.09×x) = 0.09 × 0.09×√z, then the value of x/y is____.​
OLEGan [10]

Given that-

√(0.09×0.09×x) = 0.09×0.09×√z

On squaring both sides then

⇛[√(0.09×0.09×x) ]² = (0.09×0.09×√z)²

⇛ 0.09×0.09×x= (0.09)²×(0.09)²×(√z)²

⇛ (0.09)² × x = (0.09)²×(0.09)²×z

⇛ (0.09)² × x/z = (0.09)²×(0.09)²

⇛x/z = (0.09)²×(0.09)²/(0.09)²

⇛x/z = (0.09)²

⇛x/z = 0.09×0.09

⇛x/z = 0.0081

<u>Answer</u><u>:</u><u>-</u> Hence the value of x/z will be 0.0081 r respectively.

3 0
3 years ago
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