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3 years ago

Every student in the 6th grade at PS 500 must read exactly three of the principal's four

Mathematics

1 answer:

Vladimir [108]3 years ago

6 0

Answer:

Step-by-step explanation:

I'm stuck and this is hard

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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 equation represents the relationship between z and y shown in the table?

Rina8888 [55]

Answer:

its c

Step-by-step explanation:

to took it

4 0

3 years ago

Read 2 more answers

An automobile company hired an advertising agency to survey its customers to find out which brand of tire they preferred for the

alexandr1967 [171]

A:the mean and that’s all I know ahahahahahahahhbbahhhh

7 0

3 years ago

Read 2 more answers

8,4,6,2 witch is not an composite number

liberstina [14]

Composite numbers are numbers that have more than 2 factors. With that being said, your answer would be 2.

4 is a composite number: 1, 2, 4

6 is a composite number: 1, 2, 3, 6

8 is a composite number: 1, 2, 4, 8

2 is a prime number: 1 and 2

2 is a prime number, not a composite number.

7 0

2 years ago

yuradex [85]

Answer:

B (1 , 3) , D (1 , -2)

Step-by-step explanation:

∵ A (-3 , 3) , C (-3 , -2)

∵ They have the same x-coordinate

∴ AC is a vertical segment its length = 3 - -2 = 5

∵ The area of the rectangle = 20

∴ The width of it = 20 ÷ 5 = 4

∴ x-coordinate of B: -3 + 4 = 1

∴ y-coordinate of B : 3 ⇒ AB horizontal segment

∴ B (1 , 3)

∵ x-coordinate of BD is 1 ⇒ BD is vertical segment

∵ y-coordinate = 3 - 5 = -2

∴ D (1 , -2)

3 0

3 years ago

Read 2 more answers