What does this equal to

sin alpha = 7/25, alpha lies in quadrant ii, and cos beta = 2/5, beta lies in quadrant i. find cos(alpha-beta).

Ilia_Sergeevich [38]

Answer:

Therefore $\cos(\alpha-\beta)=\frac{48+7\sqrt{25}}{125}$

Step-by-step explanation:

Given values are

$\sin \alpha=\frac{7}{25}$

$\cos \beta=\frac{2}{5}$

$\sin^2x+\cos^2=1$

$\cos \alpha=\sqrt{1-\sin^2\alpha}$

$\cos \alpha=\sqrt{1-(\frac{7}{25})^2}$

$\cos \alpha=\sqrt{1-\frac{49}{625}}$

$\cos \alpha=\sqrt{\frac{576}{625}}$

$\cos \alpha=\frac{24}{25}$

$\sin \beta=\sqrt{1-\cos^2\beta}$

$\sin \beta=\sqrt{1-(\frac{2}{5})^2}$

$\sin \beta=\sqrt{1-\frac{4}{25}}$

$\sin \beta=\frac{\sqrt{21}}{5}$

$\cos(\alpha-\beta)=\cos\alpha\cos\beta+\sin\alpha\sin\beta$

$\cos(\alpha-\beta)=\frac{24}{25}\times\frac{2}{5}+\frac{7}{25}\times\frac{\sqrt{21}}{5}$

$\cos(\alpha-\beta)=\frac{48+7\sqrt{25}}{125}$

7 0

3 years ago

PLSSS HELP IF YOU TURLY KNOW THISS

STALIN [3.7K]

Answer:

32

Step-by-step explanation:

this expression cannot be simplified because there are no like terms to combine with the numbers in the expression.

the number that goes in the ? is 32

4 0

1 year ago

Factor completely. 3x^2-3x-18 HINT: Factor out the greatest common factor first.

lubasha [3.4K]

Answer:

3(x - 3)(x + 2)

Step-by-step explanation:

take out a common factor of 3 from each term

= 3(x² - x - 6)

to factor the quadratic consider the factors of - 6 which sum to - 1

These are - 3 and + 2, hence

3x² - 3x - 18 = 3(x - 3)(x + 2) ← in factored form

3 0

3 years ago

The sum of 32 and 5 times a number is 17

Mrrafil [7]

"Sum of 32 and 5 times a number " translates to:

(32 + 5) × n

Then, it says "is 17"

So, (32 + 5) × n = 17. Let's solve!

32 + 5 = 37

37 × n = 17

To find n, we just divide 17 by 37. However, that equates to a repeating decimal, so it is best to put the answer as:

$\frac{17}{37}$

7 0

3 years ago

Bones Brothers & Associates prepare individual tax returns. Over prior years, Bones Brothers have maintained careful records

madreJ [45]

Answer:

For this case we have the following info related to the time to prepare a return

$\mu =90 , \sigma =14$

And we select a sample size =49>30 and we are interested in determine the standard deviation for the sample mean. From the central limit theorem we know that the distribution for the sample mean $\bar X$ is given by:

$\bar X \sim N(\mu, \frac{\sigma}{\sqrt{n}})$

And the standard deviation would be:

$\sigma_{\bar X} =\frac{14}{\sqrt{49}}= 2$

And the best answer would be

b. 2 minutes

Step-by-step explanation:

Previous concepts

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The central limit theorem states that "if we have a population with mean μ and standard deviation σ and take sufficiently large random samples from the population with replacement, then the distribution of the sample means will be approximately normally distributed. This will hold true regardless of whether the source population is normal or skewed, provided the sample size is sufficiently large".

Solution to the problem

For this case we have the following info related to the time to prepare a return

$\mu =90 , \sigma =14$

And we select a sample size =49>30 and we are interested in determine the standard deviation for the sample mean. From the central limit theorem we know that the distribution for the sample mean $\bar X$ is given by:

$\bar X \sim N(\mu, \frac{\sigma}{\sqrt{n}})$

And the standard deviation would be:

$\sigma_{\bar X} =\frac{14}{\sqrt{49}}= 2$

And the best answer would be

b. 2 minutes

3 0

3 years ago