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3 years ago

I neeed helppppp nowwwwww

Mathematics

2 answers:

weeeeeb [17]3 years ago

3 0

Answer:

Step-by-step explanation:

vagabundo [1.1K]3 years ago

3 0

Answer:

Step-by-step explanation:

its really simple to tell which one it is

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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

3 years ago

which expression is irrational the square root of 2 the square root of 4 the square root of 484 the square root of 529

Marina CMI [18]

If i try i think its the square root of 2 is irrational...

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3 years ago

In the expression , 5.28 x 10^3 , which number is the base ?

solong [7]

Bse is 10
x^m, x is base of exponent

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3 years ago

What is the value of x?

Ksenya-84 [330]

Step-by-step explanation:

$\frac{360 - 2(x + 30)}{2} = x \\ 360 - 2x - 60 = 2x \\ 300 - 4x = 0 \\ 4x = 300 \\ x = 300 \div 4 = 75$

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3 years ago

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Find the pay per hour if you earned $120.67 for 16 hours worked.

JulsSmile [24]

Answer:

$7.54 is the right answer

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3 years ago

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