Answer:
D
Step-by-step explanation:
We are given that:

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:

Using double angle identities:

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:

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>

</h2>
Simplify:

Evaluate:

The final answer is positive, so we can eliminate A and B.
We can simplify D to:

So, our answer is D.
Answer:
D
Step-by-step explanation:
Answer:
x = 8
Step-by-step explanation:
If the number 212x5 is a multiple of 3, the sum of the digits needs to be a multiple of 3, so we have:
2 + 1 + 2 + x + 5 = 10 + x
The value of x can be 2, 5 or 8
If the number is a multiple of 11, we have to calculate the first number minus the second, plus the third, minus the fourth... and so on, and the result needs to be a multiple of 11. So we have:
2 - 1 + 2 - x + 5 = 8 - x
x needs to be 8, so we have 8 - 8 = 0, that is a multiple of 11.
So the value of x is 8.
Answer:
x = 5
Step-by-step explanation:
x is the length of the hypotenuse of this triangle. The length of one of the legs of the triangle is 3" and that of the other leg is 4".
Applying the Pythagorean Theorem: x^2 = 3^2 + 4^2, or 25
Thus, the length x is +√25, or 5.
x = 5