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3 years ago

Somebody i need help please help me don't make brainly useless

Mathematics

1 answer:

Studentka2010 [4]3 years ago

5 0

Answer:

Triangle ABD is isosceles with AB = AD

=> angle ADB = angle ABD = 72 deg

The sum of 3 angles inside triangle ABD is equal to 180 deg

=> angle BAD + angle ADB + angle ABD = 180 deg

=> angle BAD = 180 - angle ADB - angle ABD = 180 - 72 -72 = 36 deg

Triangle ABC is isosceles with BA = BC

=> angle BCA = angle BAC = angle BAD = 36 deg

=> angle BCD = angle BCD = 36 deg (1)

The sum of 3 angles inside triangle ABC is equal to 180 deg

=> angle ABC + angle BCA + angle BAC = 180 deg

=> angle ABC = 180 - angle BCA - angle BAC = 180 - 36 - 36 = 108 deg

As shown in picture,

angle ABD + angle CBD = angle ABC

=> angle CBD = angle ABC - angle ABD = 108 - 72 = 36 deg (2)

From (1) and (2)

=> angle CBD = angle BCD = 36 deg

=> triangle CDB is isosceles with DC = DB

Hope this helps!

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The Duquesne Incline in Pittsburgh, Pennsylvania, has an angle of elevation of 30º. The track has a length of about 800 feet. Fi

Roman55 [17]

Answer:

The height of the incline is 462 feet

Step-by-step explanation:

Here, we are asked to calculate height, given the angle of elevation.

When we talk about angle of elevation, we refer to the observation angle that we have when we look up from a position which is at the base.

Please check attachment for diagrammatic representation of the question terms.

From the attachment, we can see that we have a right angled triangle. We are asked to calculate the opposite given the adjacent.

Thus the trigonometric identity to use is the Tangent

Tan 30 = h/800

h = 800 * Tan 30 = 461.88 approximately 462 feet

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4 years ago

the federal helium reserve held about 20 billion cubic feet of helium in 2010 and is being depleted by about 1.9 billion cubic f

Naya [18.7K]

The linear equation for the remaining Federal Helium Reserves, r(t) = 20 -1.9t

There is 20 billion cubic feet of Helium in 2010. Helium is depleted by about 1.9 billion cubic feet each year.

Let 'r' denotes the remaining Federal Helium Reserves in billions of cubic feet.

Let 't' denotes the number of years since 2010.

We have to find a linear equation to represent the depletion of Helium through years since 2010. A linear equation will have two variables, one dependent and one independent variable. Here, let 'r' be the dependent variable and 't' be the independent variable.

Then the amount of Helium depleted in 't' years = 1.9t

So, the remaining Helium in the Federal Helium Reserve since 2010 = 20 - 1.9t.

Thus, r(t) = 20 - 1.9t

This is a linear equation because it depends on only one variable, 't'.

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#SPJ4

3 0

2 years ago

Answer plz no try to hack me

agasfer [191]

Answer:

8/2

Step-by-step explanation:

So you'll want to multiply the number of keys for each by the number below them. So 2/8 has 4 "x"s, so you'll want to multiply (2/8)*4 and so on.

4*(2/8)=1

4*(3/8)=12/8=>1.5

1*(4/8)=1/2

Add those all up to get 4, which is also 8/2.

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3 years ago

A museum employee surveys a random sample of 350 visitors to the museum. Of those visitors, 266 stopped at the gift shop. Based

rjkz [21]

Answer: 1748.

Step-by-step explanation: This is because 266 is 76% of 350, so 76% of 2300 is 1748.

Hope that helped you out!

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3 years ago

If Matthew decided to put his $10,000 underneath the mattress, what is his future value of that money worth after forty years la

sveticcg [70]

Answer:

Step-by-step explanation:

$2,909

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3 years ago