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3 years ago

Find the exact value of tan22.5 using the half angle formula.

2 answers:

mote1985 [20]3 years ago

7 0

Tan(a/2) = sin a / (1 + cos a)
tan(45/2) = sin(45) / (1 + cos(45)) = (1/√2) / (1 + 1/√2) = (1/√2) / (√2 + 1)/√2 = 1/(√2 + 1) = (√2 - 1)

marta [7]3 years ago

3 0

Answer:

C on Edge

Step-by-step explanation:

I got it right on the test

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-6 plus 15 plus 15 equal

nikdorinn [45]

Answer would be 24 hope this is right

6 0

3 years ago

Read 2 more answers

Find the Fourier series of f on the given interval. f(x) = 1, ?7 < x < 0 1 + x, 0 ? x < 7

Zolol [24]

$f(x)=\begin{cases}1&\text{for }-7$

The Fourier series expansion of $f(x)$ is given by

$\dfrac{a_0}2+\displaystyle\sum_{n\ge1}a_n\cos\frac{n\pi x}7+\sum_{n\ge1}b_n\sin\frac{n\pi x}7$

where we have

$a_0=\displaystyle\frac17\int_{-7}^7f(x)\,\mathrm dx$
$a_0=\displaystyle\frac17\left(\int_{-7}^0\mathrm dx+\int_0^7(1+x)\,\mathrm dx\right)$
$a_0=\dfrac{7+\frac{63}2}7=\dfrac{11}2$

The coefficients of the cosine series are

$a_n=\displaystyle\frac17\int_{-7}^7f(x)\cos\dfrac{n\pi x}7\,\mathrm dx$
$a_n=\displaystyle\frac17\left(\int_{-7}^0\cos\frac{n\pi x}7\,\mathrm dx+\int_0^7(1+x)\cos\frac{n\pi x}7\,\mathrm dx\right)$
$a_n=\dfrac{9\sin n\pi}{n\pi}+\dfrac{7\cos n\pi-7}{n^2\pi^2}$
$a_n=\dfrac{7(-1)^n-7}{n^2\pi^2}$

When $n$ is even, the numerator vanishes, so we consider odd $n$ , i.e. $n=2k-1$ for $k\in\mathbb N$ , leaving us with

$a_n=a_{2k-1}=\dfrac{7(-1)-7}{(2k-1)^2\pi^2}=-\dfrac{14}{(2k-1)^2\pi^2}$

Meanwhile, the coefficients of the sine series are given by

$b_n=\displaystyle\frac17\int_{-7}^7f(x)\sin\dfrac{n\pi x}7\,\mathrm dx$
$b_n=\displaystyle\frac17\left(\int_{-7}^0\sin\dfrac{n\pi x}7\,\mathrm dx+\int_0^7(1+x)\sin\dfrac{n\pi x}7\,\mathrm dx\right)$
$b_n=-\dfrac{7\cos n\pi}{n\pi}+\dfrac{7\sin n\pi}{n^2\pi^2}$
$b_n=\dfrac{7(-1)^{n+1}}{n\pi}$

So the Fourier series expansion for $f(x)$ is

$f(x)\sim\dfrac{11}4-\dfrac{14}{\pi^2}\displaystyle\sum_{n\ge1}\frac1{(2n-1)^2}\cos\frac{(2n-1)\pi x}7+\frac7\pi\sum_{n\ge1}\frac{(-1)^{n+1}}n\sin\frac{n\pi x}7$

3 0

3 years ago

What is m<BCD<br>OA) 80°<br>OB) 90°<br>C) 100°<br>D) 110°

wlad13 [49]

Answer:

Step-by-step explanation:

The external angle of a triangle is equal to the sum of the 2 opposite interior angles.

∠ BCD is an exterior angle of the triangle, thus

∠ BCD = 50° + 60 = 110° → D

6 0

3 years ago

I don't understand pls help

MrMuchimi

Twilight was liked by half the class because if you add up the number of students you get 24 and half of 24 is 12
(Hope this helped)

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3 years ago

Ben graphed a system of equations and stated that the solution is (4, 4). Check his solution algebraically.

Juliette [100K]

A.
The graph of y= -1/2+5 is incorrect.

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3 years ago