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2 years ago

D How much money would Ashley have If she saved for 7 weeks?

1 answer:

4 0

Answer: Well it does depend on how much she gets per week, but whatever the amount she gets per week just times the number she gets per week by 7 and you should get the right answer.

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Work out the gradient of straight line AB where A=(-3,7) and B=(7,-8)

jolli1 [7]

I think it’s asking for you to multiply (-3,7) and (7,-8)
So if it is it would be -21 times-56= 1,176 AB=1,176

7 0

3 years ago

Rewrite with only sin x and cos x.

Annette [7]

Option A

$\cos 3 x=\cos x-4 \cos x \sin ^{2} x$

<em><u>Solution:</u></em>

Given that we have to rewrite with only sin x and cos x

Given is cos 3x

$cos 3x = cos(x + 2x)$

We know that,

$\cos (a+b)=\cos a \cos b-\sin a \sin b$

Therefore,

$\cos (x+2 x)=\cos x \cos 2 x-\sin x \sin 2 x$ ---- eqn 1

We know that,

$\sin 2 x=2 \sin x \cos x$

$\cos 2 x=\cos ^{2} x-\sin ^{2} x$

Substituting these values in eqn 1

$\cos (x+2 x)=\cos x\left(\cos ^{2} x-\sin ^{2} x\right)-\sin x(2 \sin x \cos x)$ -------- eqn 2

We know that,

$\cos ^{2} x-\sin ^{2} x=1-2 \sin ^{2} x$

Applying this in above eqn 2, we get

$\cos (x+2 x)=\cos x\left(1-2 \sin ^{2} x\right)-\sin x(2 \sin x \cos x)$

$\begin{aligned}&\cos (x+2 x)=\cos x-2 \sin ^{2} x \cos x-2 \sin ^{2} x \cos x\\\\&\cos (x+2 x)=\cos x-4 \sin ^{2} x \cos x\end{aligned}$

$\cos (x+2 x)=\cos x-4 \cos x \sin ^{2} x$

Therefore,

$\cos 3 x=\cos x-4 \cos x \sin ^{2} x$

Option A is correct

7 0

2 years ago

Given the lengths of two sides of a triangle, find the range for the length of the third side (between what two numbers should t

frozen [14]

Answer:

The length of the third side of given triangle lies between 6.5 and 19.9.

Step-by-step explanation:

The law of cosine is as follows

$c^{2} =a^{2}+b^{2}+2abcos\alpha$ ---------------1

⇒ a and b are the given sides of the triangle and c is the third side, and $\alpha$ is the angle between a and b .

In equation 1 , the maximum and minimum values of $cos\alpha$ are 1 and -1.

so the value of c lies in between

⇒ $\sqrt{a^{2}+b^{2}-2ab }$ and $\sqrt{a^{2}+b^{2}+2ab }$ = $|a-b| and |a+b|$

Given a=13.2 and b=6.7 so the the side lies in between |13.2-6.7| and |13.2+6.7|

so the third side lies between 6.5 and 19.9

3 0

3 years ago

Help me with this question please

Gala2k [10]

The answer is C
Hope this helped

3 0

3 years ago

Read 2 more answers

Need help with this math please.

Cerrena [4.2K]

Answer:

Do what it says and i'll give you the answer.

Step-by-step explanation:

1. Because the slopes are negative recipricals of each other then these lines are perpendicular. y=x+7 (red line) y=-x+2 (green line) +graph%28+300%2C ...

4 0

3 years ago