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2 years ago

ON TIMER!!!

Mathematics

1 answer:

Anton [14]2 years ago

8 0

Answer:

I'm sure it is 180 degrees

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Define composite figure

Shkiper50 [21]

Answer:

A figure or shape that can be divided into more than one of the basic figures, which is said to be a composite figure.

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3 years ago

Do 4x and 15 + x have the same value if x is 5?

Cerrena [4.2K]

Yes because 4 times 5 is 20 and 15 + 5 is 20

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2 years ago

Two airplanes start at the same place and travel in opposite directions,one at 395 miles per hour and the other at 422 miles per

Hitman42 [59]

plane 1 travels 395 miles in 1 hour

plane 2 travels 422 miles in 1 hour

together, they travel (395+422) 817 miles in 1 hour

to have 2451 miles between then, they'd need to travel

$\frac{2451 miles}{817 miles}=3$

so in 3 hours, they'll be 2451 miles apart

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3 years ago

Evaluate the surface integral:S

rjkz [21]

Assuming $S$ does not include the plane $z=0$ , we can parameterize the region in spherical coordinates using

$\mathbf r(u,v)=\left\langle3\cos u\sin v,3\sin u\sin v,3\cos v\right\rangle$

where $0\le u\le2\pi$ and $0\le v\le\dfrac\pi/2$ . We then have

$x^2+y^2=9\cos^2u\sin^2v+9\sin^2u\sin^2v=9\sin^2v$
$(x^2+y^2)=9\sin^2v(3\cos v)=27\sin^2v\cos v$

Then the surface integral is equivalent to

$\displaystyle\iint_S(x^2+y^2)z\,\mathrm dS=27\int_{u=0}^{u=2\pi}\int_{v=0}^{v=\pi/2}\sin^2v\cos v\left\|\frac{\partial\mathbf r(u,v)}{\partial u}\times \frac{\partial\mathbf r(u,v)}{\partial u}\right\|\,\mathrm dv\,\mathrm du$

We have

$\dfrac{\partial\mathbf r(u,v)}{\partial u}=\langle-3\sin u\sin v,3\cos u\sin v,0\rangle$
$\dfrac{\partial\mathbf r(u,v)}{\partial v}=\langle3\cos u\cos v,3\sin u\cos v,-3\sin v\rangle$
$\implies\dfrac{\partial\mathbf r(u,v)}{\partial u}\times\dfrac{\partial\mathbf r(u,v)}{\partial v}=\langle-9\cos u\sin^2v,-9\sin u\sin^2v,-9\cos v\sin v\rangle$
$\implies\left\|\dfrac{\partial\mathbf r(u,v)}{\partial u}\times\dfrac{\partial\mathbf r(u,v)}{\partial v}\|=9\sin v$

So the surface integral is equivalent to

$\displaystyle243\int_{u=0}^{u=2\pi}\int_{v=0}^{v=\pi/2}\sin^3v\cos v\,\mathrm dv\,\mathrm du$
$=\displaystyle486\pi\int_{v=0}^{v=\pi/2}\sin^3v\cos v\,\mathrm dv$
$=\displaystyle486\pi\int_{w=0}^{w=1}w^3\,\mathrm dw$

where $w=\sin v\implies\mathrm dw=\cos v\,\mathrm dv$ .

$=\dfrac{243}2\pi w^4\bigg|_{w=0}^{w=1}$
$=\dfrac{243}2\pi$

4 0

3 years ago

Are the following lines parallel ?

Zarrin [17]

Answer:

false jfkdigitkhijdkdkcjgjdjjbkdkvkffkb

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3 years ago

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