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3 years ago

Can someone pls help me with this thank you very much :)

Mathematics

1 answer:

liberstina [14]3 years ago

7 0

Answer:

Step-by-step explanation:

M O N K I E

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Use green's theorem to compute the area inside the ellipse x252+y2172=1. use the fact that the area can be written as ∬ddxdy=12∫

Pavel [41]

The area of the ellipse $E$ is given by

$\displaystyle\iint_E\mathrm dA=\iint_E\mathrm dx\,\mathrm dy$

To use Green's theorem, which says

$\displaystyle\int_{\partial E}L\,\mathrm dx+M\,\mathrm dy=\iint_E\left(\frac{\partial M}{\partial x}-\frac{\partial L}{\partial y}\right)\,\mathrm dx\,\mathrm dy$

( $\partial E$ denotes the boundary of $E$ ), we want to find $M(x,y)$ and $L(x,y)$ such that

$\dfrac{\partial M}{\partial x}-\dfrac{\partial L}{\partial y}=1$

and then we would simply compute the line integral. As the hint suggests, we can pick

$\begin{cases}M(x,y)=\dfrac x2\\\\L(x,y)=-\dfrac y2\end{cases}\implies\begin{cases}\dfrac{\partial M}{\partial x}=\dfrac12\\\\\dfrac{\partial L}{\partial y}=-\dfrac12\end{cases}\implies\dfrac{\partial M}{\partial x}-\dfrac{\partial L}{\partial y}=1$

The line integral is then

$\displaystyle\frac12\int_{\partial E}-y\,\mathrm dx+x\,\mathrm dy$

We parameterize the boundary by

$\begin{cases}x(t)=5\cos t\\y(t)=17\sin t\end{cases}$

with $0\le t\le2\pi$ . Then the integral is

$\displaystyle\frac12\int_0^{2\pi}(-17\sin t(-5\sin t)+5\cos t(17\cos t))\,\mathrm dt$

$=\displaystyle\frac{85}2\int_0^{2\pi}\sin^2t+\cos^2t\,\mathrm dt=\frac{85}2\int_0^{2\pi}\mathrm dt=85\pi$

###

Notice that $x^{2/3}+y^{2/3}=4^{2/3}$ kind of resembles the equation for a circle with radius 4, $x^2+y^2=4^2$ . We can change coordinates to what you might call "pseudo-polar":

$\begin{cases}x(t)=4\cos^3t\\y(t)=4\sin^3t\end{cases}$

which gives

$x(t)^{2/3}+y(t)^{2/3}=(4\cos^3t)^{2/3}+(4\sin^3t)^{2/3}=4^{2/3}(\cos^2t+\sin^2t)=4^{2/3}$

as needed. Then with $0\le t\le2\pi$ , we compute the area via Green's theorem using the same setup as before:

$\displaystyle\iint_E\mathrm dx\,\mathrm dy=\frac12\int_0^{2\pi}(-4\sin^3t(12\cos^2t(-\sin t))+4\cos^3t(12\sin^2t\cos t))\,\mathrm dt$

$=\displaystyle24\int_0^{2\pi}(\sin^4t\cos^2t+\cos^4t\sin^2t)\,\mathrm dt$

$=\displaystyle24\int_0^{2\pi}\sin^2t\cos^2t\,\mathrm dt$

$=\displaystyle6\int_0^{2\pi}(1-\cos2t)(1+\cos2t)\,\mathrm dt$

$=\displaystyle6\int_0^{2\pi}(1-\cos^22t)\,\mathrm dt$

$=\displaystyle3\int_0^{2\pi}(1-\cos4t)\,\mathrm dt=6\pi$

3 0

3 years ago

Tthe rectangle below has an area of 12y^5 square meters and a width of 3y^3 meters

liq [111]

Answer:

$4y^2$

Step-by-step explanation:

$length \: of \: rectangle \\ = \frac{area}{width} \\ \\ = \frac{12 {y}^{5} }{3 {y}^{3} } \\ \\ = 4 {y}^{5-3} \\ \\ \red{ \bold{ length \: of \: rectangle = 4 {y}^{2} }}$

6 0

3 years ago

A government official is in charge of allocating social programs throughout the city of Vancouver. He will decide where these so

otez555 [7]

Answer: (0.132132, 0.274368)

Step-by-step explanation:

Given : A simple random sample of 123 people living in Gastown and finds that 25 have an annual income that is below the poverty line.

i.e. n= 123

$\hat{p}=\dfrac{25}{123}\approx0.203252$

Critical value for 95% confidence interval : $z_{\alpha/2}=1.96$

Confidence interval for population :

$\hat{p}\pm z_{\alpha/2}\sqrt{\dfrac{\hat{p}(1-\hat{p})}{n}}$

i.e. $0.203252\pm (1.96)\sqrt{\dfrac{0.203252(1-0.203252)}{123}}$

$0.203252\pm (1.96)\sqrt{\dfrac{0.203252(1-0.203252)}{123}}\\\\\0.203252\pm0.071118\\\\=(0.20325-0.071118,\ 0.203252+0.071118)\\\\=(0.132132,\ 0.274368)$

Hence, the 95% confidence interval for the true proportion of Gastown residents living below the poverty line : (0.132132, 0.274368)

5 0

3 years ago

Round 36 to the nearest hundredth. for the brainiest

mestny [16]

36 to the nearest hundredth is just 36

To round 36 to the nearest hundredth consider the thousandths' value of 36, which is 0 and less than 5. Therefore, the hundredths' value of 36 remains 36

6 0

3 years ago

Read 2 more answers

What is the answer to 5x6+6x3+4x9

juin [17]

Use order of operations
P
E
M
D
A
S

So multiply 5x6 to get 30
Then times 6x3 to get 18
Next times 4x9 to get 36

Add 30, 18, and 36 together to get

84

8 0

3 years ago

Read 2 more answers

Can someone pls help me with this thank you very much :)​

Can someone pls help me with this thank you very much :)