Simplification of trigonometric expression cos²θ - 1 = cos(2θ) - cos²θ.
For simplifying the trigonometric expression cos²θ - 1, we can use the Pythagorean Identity.
The Pythagorean Identity states that cos²θ + sin²θ = 1.
Now, let's rewrite the expression using the Pythagorean Identity:
cos²θ - 1 = cos²θ - sin²θ + sin²θ - 1
Next, we can group the terms together:
cos²θ - sin²θ + sin²θ - 1 = (cos²θ - sin²θ) + (sin²θ - 1)
Now, let's simplify each group:
Group 1: cos²θ - sin²θ = cos(2θ) [using the double angle formula for cosine]
Group 2: sin²θ - 1 = -cos²θ [using the Pythagorean Identity sin²θ = 1 - cos²θ]
Therefore, the simplified expression is:
cos²θ - 1 = cos(2θ) - cos²θ
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13. Find the sum of the arithmetic
sequence 4, 1, -2, -5,. , -56.
-777-3,3-3,
A
B
-546
C -542
D -490
The sum of the arithmetic sequence is -468 (option D).
To find the sum of an arithmetic sequence, we can use the formula:
Sum = (n/2) * (first term + last term)
In this case, the first term of the sequence is 4, and the common difference between consecutive terms is -3. We need to find the last term of the sequence.
To find the last term, we can use the formula for the nth term of an arithmetic sequence:
last term = first term + (n - 1) * common difference
In this case, the last term is -56. We can use this information to find the number of terms (n) in the sequence:
-56 = 4 + (n - 1) * (-3)
-56 = 4 - 3n + 3
-56 - 4 + 3 = -3n
-53 = -3n
n = -53 / -3 = 17.67
Since the number of terms should be a whole number, we round up to the nearest whole number and get n = 18.
Now, we can find the sum of the arithmetic sequence:
Sum = (18/2) * (4 + (-56))
Sum = 9 * (-52)
Sum = -468
Therefore, the sum of the arithmetic sequence is -468 (option D).
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Suppose that in a particular sample, the mean is 50 and the standard deviation is 10. What is the z score associated with a raw score of 68?
The z-score associated with a raw score of 68 is 1.8.
Given mean = 50 and standard deviation = 10.
Z-score is also known as standard score gives us an idea of how far a data point is from the mean. It indicates how many standard deviations an element is from the mean. Hence, Z-Score is measured in terms of standard deviation from the mean.
The formula for calculating the z-score is given as
z = (X - μ) / σ
where X is the raw score, μ is the mean and σ is the standard deviation.
In this case, the raw score is X = 68.
Substituting the given values in the formula, we get
z = (68 - 50) / 10
z = 18 / 10
z = 1.8
Therefore, the z-score associated with a raw score of 68 is 1.8.
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