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QveST [7]
3 years ago
5

Suppose cos(x)= -1/3, where π/2 ≤ x ≤ π. What is the value of tan(2x). EDGE

Mathematics
1 answer:
AVprozaik [17]3 years ago
7 0

Answer:

D

Step-by-step explanation:

We are given that:

\displaystyle \cos x = -\frac{1}{3}\text{ where } \pi /2 \leq x \leq \pi

And we want to find the value of tan(2<em>x</em>).

Note that since <em>x</em> is between π/2 and π, it is in QII.

In QII, cosine and tangent are negative and only sine is positive.

We can rewrite our expression as:

\displaystyle \tan(2x)=\frac{\sin(2x)}{\cos(2x)}

Using double angle identities:

\displaystyle  \tan(2x)=\frac{2\sin x\cos x}{\cos^2 x-\sin^2 x}

Since cosine relates the ratio of the adjacent side to the hypotenuse and we are given that cos(<em>x</em>) = -1/3, this means that our adjacent side is one and our hypotenuse is three (we can ignore the negative). Using this information, find the opposite side:

\displaystyle o=\sqrt{3^2-1^2}=\sqrt{8}=2\sqrt{2}

So, our adjacent side is 1, our opposite side is 2√2, and our hypotenuse is 3.

From the above information, substitute in appropriate values. And since <em>x</em> is in QII, cosine and tangent will be negative while sine will be positive. Hence:

<h2>\displaystyle  \tan(2x)=\frac{2(2\sqrt{2}/3)(-1/3)}{(-1/3)^2-(2\sqrt{2}/3)^2}</h2>

Simplify:

\displaystyle  \tan(2x)=\frac{-4\sqrt{2}/9}{(1/9)-(8/9)}

Evaluate:

\displaystyle  \tan(2x)=\frac{-4\sqrt{2}/9}{-7/9} = \frac{4\sqrt{2}}{7}

The final answer is positive, so we can eliminate A and B.

We can simplify D to:

\displaystyle \frac{2\sqrt{8}}{7}=\frac{2(2\sqrt{2}}{7}=\frac{4\sqrt{2}}{7}

So, our answer is D.

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2 years ago
Mathematics, Help, not sure about my answer on this one
olga nikolaevna [1]

Answer:

F. 2 1/9

Step-by-step explanation:

Step 1: Substitute q

r = 3(\frac{1}{3^n} )+2

When you plug in <em>n</em> = 1, 2, 3:

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n(2) = 2.11111

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So our answer is F.

3 0
3 years ago
Faron wants to paint the four walls in his bedroom. The room measures 12 ft long, 10 ft wide and 8 ft high. There are two doors
Rainbow [258]

Answer:

319 square feet.

Step-by-step explanation:

The walls of the room (the ones on the long side) have an area of 12 x 8 = 96 square feet each one. Thus, their area is 96 x 2= 192 square feet.

The other two walls have an area of 10 x 8 = 80 square feet each one. Thus, their area combined is 80 x 2 = 160 square feet.

Therefore, we have that the total area of the four walls is

192 +160 = 352 square feet

However, we have a door and a window that won't be painted.

The area of the door is: 3 x 7 =21 square feet

The area of the window is 3 x 4 = 12 square feet

Thus, the total amount of area that won't be painted is

21 + 12 = 33 square feet.

So we are going to take the total area minus the area that won't be painted to know the total area that Faron will pain:

352 - 33 = 319 square feet.

Thus, she will paint 319 square feet

4 0
3 years ago
What is the value of the expression <br> 7⋅(−5)⋅4?
Masja [62]
Multiply each number. Remember that when multiplying a negative and positive number, the outcome will be negative

7 x -5 = -35
-35 x 4 = -140

-140 is your answer

hope this helps
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