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Mathematics

1 answer:

Volgvan3 years ago

8 0

Answer:

5cm

Step-by-step explanation:

volume = πr²h

225π = π × r² × 9

225/9 = r²

r = √225/9 = 15/3 = 5cm

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[TON OF POINTS] [3 QUESTIONS - Easy money :)]

kherson [118]

The correct answers are:

1/6πd³;
3; and
9 cm.

Explanation:

For the first question:

The formula for the volume of a sphere is:

$V=\frac{4}{3}\pi r^3$

We have the diameter, not the radius. The diameter is twice as much as the radius; this means to find the radius using the diameter, we divide by 2. This gives us:

$V=\frac{4}{3}\pi (\frac{d}{2})^3$

When we raise a fraction to a power, we raise both the numerator and the denominator to that power. This gives us:

$V=\frac{4}{3}\pi(\frac{d^3}{2^3})
\\
\\=\frac{4}{3}\pi(\frac{d^3}{8})$

We start multiplying this:
$V=\frac{4\pi}{3}(\frac{d^3}{8})
\\
\\=\frac{4\pi d^3}{3\times 8}
\\
\\=\frac{4\pi d^3}{24}
\\
\\=\frac{4}{24}\pi d^3
\\
\\=\frac{1}{6}\pi d^3$

For the second question:

The planes of symmetry are the planes through which we can fold the figure in half. These are in the middle horizontally through the figure; in the middle vertically (through the width) through the figure; and in the middle vertically (through the length) through the figure. This makes 3.

For the third question:

The formula for the volume of a triangular prism is:

$V=\frac{1}{3}(\frac{1}{2}bh)H$ ,

where b is the base of the triangular base of the pyramid, h is the height of the triangular base of the pyramid, and H is the height of the pyramid.

We know the volume is 90; the base of the triangle is 12 and the height is 5:

$90 = \frac{1}{3}(\frac{1}{2}\times 12\times 5)H
\\
\\90 = \frac{1}{3}(\frac{1}{2}\times 60)H
\\
\\90 = \frac{1}{3}(30)H
\\
\\90 = 10H$

We divide both sides by 10:

90/10 = 10H/10
9 = H

4 0

4 years ago

I remember all the boys used to like this one girl in 6th grade because she was already full developed and she had curly hair an

agasfer [191]

Answer:

Wow that's messed up and was she black or white

4 0

3 years ago

I need help with this question!!!

USPshnik [31]

Answer: 5x - 2

Step-by-step explanation:

So area is length*width, we have the area and length which is 5x^2 + 43x - 18 and x + 9. So we need to divide. First the x, what times x is 5x^2? 5x, x*x is x squared. Then we need to apply the 5x to 9. 5x*9 is 45x, and we can’t do anything to the 18 because 18/5 is a decimal. After that we subtract the new area with the old one. 5x^2 + 43x - 18 minus 5x^2 + 45x which is -2x - 18. Now we divide the -18 with 9 which is -2. Remember the 5x we had from using the x? We put that and -2 together which is 5x-2, and that’s your width. Hope this helped!

7 0

2 years ago

An earth satellite remains in orbit at a distance of 11550 km from the center of the earth. what speed would it have to maintain

marishachu [46]

11,550 km has to be changed to 11,550,000 meters

G · m · t² = 4 · π² · r³ we can change that to
t² = (4 · π² · r³) / (G · m )
t^2 = 4*PI^2*r^3 / (G*m)
t^2 = 4*PI^2*(11,550,000)^3 / 6.67*10^-11*5.98*10^24kg
t^2 = 6.083*10^22 / 3.99 * 10^14
t^2 = 152,500,000
t = 12,350 seconds
and its orbital distance it travels is 11,550 * 2*PI = 70,050 kilometers

Therefore, it is traveling at 70,050 km / 12,350 second which equals
5.67 km per second which is 5,670 meters per second.

Source:
http://www.1728.org/kepler3a.htm

4 0

4 years ago

A rectangular garden has an area of 72 square feet. Joe planted of the garden with vegetables and of the garden with flowers. Wh

Cerrena [4.2K]

I think you left out the word half. I am going to assume you meant half. If half the garden is planted with flowers, then you take away half of the area, which would be 36. that leaves you with 36sq.ft. that he has used to plant vegetables

3 0

4 years ago