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2 years ago

Help please. im confused

Mathematics

1 answer:

Arturiano [62]2 years ago

5 0

Answer:

C is correct

Step-by-step explanation:

C means that, with one value of input x, you can have two values of output y.

That is impossible.

Hope this help!

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Answers choices <1 <4 <2 <3

Maslowich

Answer:

B) 4

Step-by-step explanation:

1. It is either 3 or 4, since those are only two angles comparing the lighthouse and the boat.

2. The angle of depression is noted below the horizontal and above the actual line, and out of 3 and 4, 4 is the only angle that is below its corresponding horizontal.

So, the angle of depression from the lighthouse to the boat is 4.

7 0

2 years ago

How to know if a function is periodic without graphing it ?

zhenek [66]

A function $f(t)$ is periodic if there is some constant $k$ such that $f(t+k)=f(k)$ for all $t$ in the domain of $f(t)$ . Then $k$ is the "period" of $f(t)$ .

Example:

If $f(x)=\sin x$ , then we have $\sin(x+2\pi)=\sin x\cos2\pi+\cos x\sin2\pi=\sin x$ , and so $\sin x$ is periodic with period $2\pi$ .

It gets a bit more complicated for a function like yours. We're looking for $k$ such that

$\pi\sin\left(\dfrac\pi2(t+k)\right)+1.8\cos\left(\dfrac{7\pi}5(t+k)\right)=\pi\sin\dfrac{\pi t}2+1.8\cos\dfrac{7\pi t}5$

Expanding on the left, you have

$\pi\sin\dfrac{\pi t}2\cos\dfrac{k\pi}2+\pi\cos\dfrac{\pi t}2\sin\dfrac{k\pi}2$

and

$1.8\cos\dfrac{7\pi t}5\cos\dfrac{7k\pi}5-1.8\sin\dfrac{7\pi t}5\sin\dfrac{7k\pi}5$

It follows that the following must be satisfied:

$\begin{cases}\cos\dfrac{k\pi}2=1\\\\\sin\dfrac{k\pi}2=0\\\\\cos\dfrac{7k\pi}5=1\\\\\sin\dfrac{7k\pi}5=0\end{cases}$

The first two equations are satisfied whenever $k\in\{0,\pm4,\pm8,\ldots\}$ , or more generally, when $k=4n$ and $n\in\mathbb Z$ (i.e. any multiple of 4).

The second two are satisfied whenever $k\in\left\{0,\pm\dfrac{10}7,\pm\dfrac{20}7,\ldots\right\}$ , and more generally when $k=\dfrac{10n}7$ with $n\in\mathbb Z$ (any multiple of 10/7).

It then follows that all four equations will be satisfied whenever the two sets above intersect. This happens when $k$ is any common multiple of 4 and 10/7. The least positive one would be 20, which means the period for your function is 20.

Let's verify:

$\sin\left(\dfrac\pi2(t+20)\right)=\sin\dfrac{\pi t}2\underbrace{\cos10\pi}_1+\cos\dfrac{\pi t}2\underbrace{\sin10\pi}_0=\sin\dfrac{\pi t}2$

$\cos\left(\dfrac{7\pi}5(t+20)\right)=\cos\dfrac{7\pi t}5\underbrace{\cos28\pi}_1-\sin\dfrac{7\pi t}5\underbrace{\sin28\pi}_0=\cos\dfrac{7\pi t}5$

More generally, it can be shown that

$f(t)=\displaystyle\sum_{i=1}^n(a_i\sin(b_it)+c_i\cos(d_it))$

is periodic with period $\mbox{lcm}(b_1,\ldots,b_n,d_1,\ldots,d_n)$ .

4 0

2 years ago

Cynthia Besch wants to buy a rug for a room that is 21 ft wide and 34 ft long. She wants to leave

Daniel [21]

Answer:

Dimensions of the rug = 13 ft × 26 ft

Step-by-step explanation:

Dimensions of the room = 21 ft × 34 ft

Area of the room = 21 × 34 = 714 ft²

Cynthia wants to leave a uniform strip of floor around the rug.

Let the width of the rug = x ft

Then the dimensions of the rug will be = (21- 2x)ft × (34 - 2x)ft

Area of the rug = (21 - 2x)×(34 - 2x) square feet

338 = (21 - 2x)×(34 - 2x)

338 = 714 - 68x - 42x + 4x²

4x² - 110x + 714 - 338 = 0

4x² - 110x + 376 = 0

2x² - 55x + 188 = 0

2x² - 47x - 8x + 188 = 0

x(2x - 47) - 8(x - 47) = 0

(x - 4)(2x - 47) = 0

x = 4, $\frac{47}{2}$

For x = 23.5 area of the rug will be negative.

Therefore, x = 4 ft will be the width of the rug.

Dimensions of the rug will be 13 ft × 26 ft.

7 0

2 years ago

Is it correct in adding subtracting?? Answer is in the picture please give me answer soon

MrRissso [65]

Answer:

8/24 is correct. However, I would simplify 8/24 down to 1/3, since most teachers want you to do that.

3 0

1 year ago

HELP ME PLEASE Select the locations on the number line to plot the points 10/2 and −9/2

mr_godi [17]

Answer:

5 and -4.5

Step-by-step explanation:

10/2= 5 -9/2 = -4.5

I really hope this helps

5 0

2 years ago