What is the slope-intercept equation of the line below

Olin [163]

With $2L=\pi$ , the Fourier series expansion of $f(x)$ is

$\displaystyle f(x)\sim\frac{a_0}2+\sum_{n\ge1}a_n\cos\dfrac{n\pi x}L+\sum_{n\ge1}b_n\sin\dfrac{n\pi x}L$
$\displaystyle f(x)\sim\frac{a_0}2+\sum_{n\ge1}a_n\cos2nx+\sum_{n\ge1}b_n\sin2nx$

where the coefficients are obtained by computing

$\displaystyle a_0=\frac1L\int_0^{2L}f(x)\,\mathrm dx$
$\displaystyle a_0=\frac2\pi\int_0^\pi f(x)\,\mathrm dx$

$\displaystyle a_n=\frac1L\int_0^{2L}f(x)\cos\dfrac{n\pi x}L\,\mathrm dx$
$\displaystyle a_n=\frac2\pi\int_0^\pi f(x)\cos2nx\,\mathrm dx$

$\displaystyle b_n=\frac1L\int_0^{2L}f(x)\sin\dfrac{n\pi x}L\,\mathrm dx$
$\displaystyle b_n=\frac2\pi\int_0^\pi f(x)\sin2nx\,\mathrm dx$

You should end up with

$a_0=0$
$a_n=0$
(both due to the fact that $f(x)$ is odd)
$b_n=\dfrac1{3n}\left(2-\cos\dfrac{2n\pi}3-\cos\dfrac{4n\pi}3\right)$

Now the problem is that this expansion does not match the given one. As a matter of fact, since $f(x)$ is odd, there is no cosine series. So I'm starting to think this question is missing some initial details.

One possibility is that you're actually supposed to use the even extension of $f(x)$ , which is to say we're actually considering the function

$\varphi(x)=\begin{cases}\frac\pi3&\text{for }|x|\le\frac\pi3\\0&\text{for }\frac\pi3$

and enforcing a period of $2L=2\pi$ . Now, you should find that

$\varphi(x)\sim\dfrac2{\sqrt3}\left(\cos x-\dfrac{\cos5x}5+\dfrac{\cos7x}7-\dfrac{\cos11x}{11}+\cdots\right)$

The value of the sum can then be verified by choosing $x=0$ , which gives

$\varphi(0)=\dfrac\pi3=\dfrac2{\sqrt3}\left(1-\dfrac15+\dfrac17-\dfrac1{11}+\cdots\right)$
$\implies\dfrac\pi{2\sqrt3}=1-\dfrac15+\dfrac17-\dfrac1{11}+\cdots$

as required.

5 0

2 years ago

Converting (x - 4)^2 + y^2 = 16 into polar form

dimulka [17.4K]

In this case, we'll have to carry out several steps to find the solution.

Step 01:

Data:

(x - 4)² + y² = 16

Step 02:

polar form:

x = r cos (θ)

y = r sin (θ)

(r cos (θ) - 4 )² + (r sin (θ))² = 16

(r cos θ - 4)² + r² sin² θ = 16

r (r - 8 cos (θ)) = 0

r = 8 cos θ

The answer is:

r = 8 cos θ

8 0

6 months ago

manuel wanted to put a brick walkway through his backyard from door to bbq area. the walkway is going to be 6 yards long. so far

In-s [12.5K]

Answer:

155 inches

Step-by-step explanation:

1 yard = 3 feet = 36 inches ; 6 yards = 18 feet = 216 inches ; 216 inches-61 inches = 155 inches

5 0

2 years ago

How many lives does a cat have, also there are 20cats in the room, how many cat lives are in the room

Andrei [34K]

Answer:

20

Step-by-step explanation:

Technically cats only have one life even though they can survive falls and such

8 0

2 years ago

Explain please and tell me how to do it ?

SCORPION-xisa [38]

The trick to calculating the area here is to subdivide the diagram into smaller parts. For example, there's a 3 cm-by-3cm square. The rectangle is 4 cm by 8 cm.. The triangle has a base of 5 cm and a height of 3 cm.

Total area = area of square + area of rectangle + area of triangle

= 9 cm^2 + 32 cm^2 + (1/2)(5 cm)(3 cm)

= (9 + 32 + 7.5) cm^2

= 48.5 cm^2 (total area of figure)

8 0

3 years ago

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