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2 years ago

7. Work out the area of the shaded shape. (2 marks) * 4 cm 6 cm 5cm 6 cm 4 cm

Mathematics

1 answer:

Ivenika [448]2 years ago

4 0

For the image above, the answer is 91°.
Since all the angles of a triangle add up to 180, we can work backwards to find the answer.
180-51-38= 91°

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Use two unit multipliers to convert 135 square miles to square feet

Inessa [10]

You only need one of them:

   (135 mile²) x (5,280 feet/mile)²

   = (135 mile²) x (27,878,400 feet²/mile²)

   = (135 x 27,878,400) mile² - feet² / mile²

   = 3,763,584,000 feet²

5 0

3 years ago

Solve using Fourier series.

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

3 years ago

which of the following is the algebraic expression that best describes the sequence 3, 9, 27, 81, 243,...?

Anton [14]

${3}^{n}$

3 0

3 years ago

Susan's investment portfolio currently contains three stocks that have a total value equal to $100,000. The beta of this portfol

Sladkaya [172]

A stock portfolio's overall beta is found by multiplying each stock's beta times the percentage of the overall portfolio it makes up and adding these terms together. Since the current portfolio's beta is known, we can treat all the stocks in the portfolio as a single stock for calculating its weight in the new portfolio. Thus, our new portfolio will have a value of $150,000, $100,000, or 2/3, of which has a beta of 1.5 and $50,000, or 1/3, of which has a beta of 3. Then the beta of the new portfolio will be 1.5*(2/3) + 3*(1/3) = 2.

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3 years ago

What is the value of any nonzero number raised to the power of 0?

Luda [366]

Any number to the power of 0 equals 1. Even if the original number is extremely high like 10000000, the value will still equal 1.

7 0

3 years ago