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2 years ago

10

A pile of sand has been stored in the shape of a cone. Mr. Terwilliker knows that the pile is 20 feet tall and 102 feet in circu

mference at the base. What is the area of the conical tarpaulin needed to cover the pile?

1 answer:

xenn [34]2 years ago

4 0

Answer:

The area of tarpaulin is 1315.63 ft^2.

Step-by-step explanation:

height, h = 20 feet

circumference, C = 102 feet

Let the radius is r.

Circumference, C = 2 x 3.14 x r = 102

r = 16.24 feet

Let the slant height is L.

$L = \sqrt{h^2 + r^2}\\\\L = \sqrt{20^2 + 16.24^2}\\\\L = 25.8 ft$

The curved surface area is

S = 3.14 x r x L

S = 3.14 x 16.24 x 25.8 = 1315.63 ft^2

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When the sun has risen 32 degrees above the horizon, Sandy casts a shadow that is 9 feet 2 inches long. How tall is Sandy, to th

Makovka662 [10]

Answer:

The height of Sandy is 68.74 inches.

Step-by-step explanation:

It is given that the sun has risen 32 degrees above the horizon. It means the angle of elevation is 32°.

Let the height of Sandy be x.

Sandy casts a shadow that is 9 feet 2 inches long.

We know that 1 feet = 12 inches

Using this conversion, we get

Shadow = 9 feet 2 inches = 9(12)+2 = 110 inches

In a right angled triangle,

$\tan\theta =\frac{perpendicular}{base}$

In triangle ABC,

$\tan(\angle C)=\frac{AB}{BC}$

$\tan(32^{\circ})=\frac{x}{110}$

Multiply both sides by 110.

$110\tan(32^{\circ})=x$

$68.73562871=x$

$x\approx 68.74$

Therefore the height of Sandy is 68.74 inches.

8 0

3 years ago

Ken and bill collected 550 stickers together. Ken collected 20% more stickers than bill. How many stickers did ken collect?

Anestetic [448]

Answer:300

Step-by-step explanation:

4 0

2 years ago

Read 2 more answers

Let f(x,y,z) = ztan-1(y2) i + z3ln(x2 + 1) j + z k. find the flux of f across the part of the paraboloid x2 + y2 + z = 3 that li

Sophie [7]

Consider the closed region $V$ bounded simultaneously by the paraboloid and plane, jointly denoted $S$ . By the divergence theorem,

$\displaystyle\iint_S\mathbf f(x,y,z)\cdot\mathrm dS=\iiint_V\nabla\cdot\mathbf f(x,y,z)\,\mathrm dV$

And since we have

$\nabla\cdot\mathbf f(x,y,z)=1$

the volume integral will be much easier to compute. Converting to cylindrical coordinates, we have

$\displaystyle\iiint_V\nabla\cdot\mathbf f(x,y,z)\,\mathrm dV=\iiint_V\mathrm dV$
$=\displaystyle\int_{\theta=0}^{\theta=2\pi}\int_{r=0}^{r=1}\int_{z=2}^{z=3-r^2}r\,\mathrm dz\,\mathrm dr\,\mathrm d\theta$
$=\displaystyle2\pi\int_{r=0}^{r=1}r(3-r^2-2)\,\mathrm dr$
$=\dfrac\pi2$

Then the integral over the paraboloid would be the difference of the integral over the total surface and the integral over the disk. Denoting the disk by $D$ , we have

$\displaystyle\iint_{S-D}\mathbf f\cdot\mathrm dS=\frac\pi2-\iint_D\mathbf f\cdot\mathrm dS$

Parameterize $D$ by

$\mathbf s(u,v)=u\cos v\,\mathbf i+u\sin v\,\mathbf j+2\,\mathbf k$
$\implies\mathbf s_u\times\mathbf s_v=u\,\mathbf k$

which would give a unit normal vector of $\mathbf k$ . However, the divergence theorem requires that the closed surface $S$ be oriented with outward-pointing normal vectors, which means we should instead use $\mathbf s_v\times\mathbf s_u=-u\,\mathbf k$ .

Now,

$\displaystyle\iint_D\mathbf f\cdot\mathrm dS=\int_{u=0}^{u=1}\int_{v=0}^{v=2\pi}\mathbf f(x(u,v),y(u,v),z(u,v))\cdot(-u\,\mathbf k)\,\mathrm dv\,\mathrm du$
$=\displaystyle-4\pi\int_{u=0}^{u=1}u\,\mathrm du$
$=-2\pi$

So, the flux over the paraboloid alone is

$\displaystyle\iint_{S-D}\mathbf f\cdot\mathrm dS=\frac\pi2-(-2\pi)=\dfrac{5\pi}2$

6 0

3 years ago

A circular pool with a diameter of 18 ft will have a uniform 4 ft concrete walkway poured around it. If the concrete cost $4.25

zysi [14]

A circular pool with a diameter of 18 ft will have a uniform 4 ft concrete walkway poured around it. If the concrete cost $4.25 a square foot, how much will it cost for the concrete?

This can be solve be solving the area of walkway

Area of walkway is equal to = (pi)( 9 ft +4) ^2– (pi)(9ft)^2

= 276.46 sq ft

Cost = 276.46 sq ft * ($4.25 a square foot) = $1174.70

4 0

3 years ago

Read 2 more answers

In this diagram which equation could you prove to be true in order to conclude that the lines are parallel

KiRa [710]

I would say that the correct answer is D. because y is always the numerator while x is the denominator for the equation y2 - y1/x2 - x1 which means if there is two y's or two x's on the same line you subtract the second one from the first one. If there is only one y and/or x and the other is 0 on the same line, it stays at y or x without subtracting y2 - y1 or x2 - x1.

Since b is on the y coordinate and -a is on the x coordinate, you would make it b/a while -a is gonna be a positive since the lines are going up and to the right. Now, since c is the y coordinate and d is the x coordinate, make C the numerator and d the denominator since y is always the numerator and x is the denominator for these parallel line figures on the graph and the equation will be equaled to the fraction to the other fraction for parallel lines.

So, your answer would be D. b/a = c/d

Hope this helps, and is correct!

<em>~ ShadowXReaper069</em>

3 0

3 years ago

Read 2 more answers