The difference of a number mand thirty is ten. How do you write this as a equation?

Find sin(2x), cos(2x), and tan(2x) from the given information.

larisa86 [58]

Since $\cot(x)=\frac{2}{3}$ and $\cot^{2} x+1=\csc^{2} x$ , we know that:

$\left(\frac{2}{3} \right)^{2}+1=\csc^{2} x\\\\\frac{13}{9}=\csc^{2} x\\\\\csc x=\frac{\sqrt{13}}{3}$

If $\csc x=\frac{\sqrt{13}}{3}$ , this means that $\sin x=\frac{3}{\sqrt{13}}$ and by the Pythagorean identity,

$\sin^{2} x+\cos^{2} x=1\\\left(\frac{3}{\sqrt{13}} \right)^{2}+\cos^{2} x=1\\\frac{9}{13}+\cos^{2} x=1\\\cos^{2} x=\frac{4}13}\\\cos x=\frac{2}{\sqrt{13}}$

Using the double angle formula for sine, $\sin(2x)=2\left(\frac{3}{\sqrt{13}} \right)\left(\frac{2}{\sqrt{13}} \right)=\boxed{\frac{12}{13}}$
Using the double angle formula for cosine, $\cos(2x)=1-2\left(\frac{3}{\sqrt{13}} \right)^{2}=\boxed{-\frac{5}{13}}$
So, since tan=sin/cos, $\tan (2x)=\frac{\sin(2x)}{\cos(2x)}=\frac{\frac{12}{13}}{-\frac{5}{13}}=\boxed{-\frac{12}{5}}$

7 0

2 years ago

A data set includes 103103 body temperatures of healthy adult humans having a mean of 98.998.9degrees°f and a standard deviation

dangina [55]

Answer:

$98.9-2.62\frac{0.65}{\sqrt{103}}=98.73$

$98.9+2.62\frac{0.65}{\sqrt{103}}=99.07$

So on this case the 99% confidence interval would be given by (98.73;99.07)

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

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".

$\bar X=98.9$ represent the sample mean for the sample

$\mu$ population mean (variable of interest)

s=0.65 represent the sample standard deviation

n=103 represent the sample size

Solution to the problem

The confidence interval for the mean is given by the following formula:

$\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}$ (1)

In order to calculate the critical value $t_{\alpha/2}$ we need to find first the degrees of freedom, given by:

$df=n-1=103-1=102$

Since the Confidence is 0.99 or 99%, the value of $\alpha=0.01$ and $\alpha/2 =0.005$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.005,102)".And we see that $t_{\alpha/2}=2.62$

Now we have everything in order to replace into formula (1):

$98.9-2.62\frac{0.65}{\sqrt{103}}=98.73$

$98.9+2.62\frac{0.65}{\sqrt{103}}=99.07$

So on this case the 99% confidence interval would be given by (98.73;99.07)

6 0

3 years ago

Read 2 more answers

A company needs $5,400,000 in 14 years in order to expand their factory. How much should the company invest each week if the inv

ludmilkaskok [199]

Answer: the company should invest $12191 each week

Step-by-step explanation:

The amount that the company needs is $5,400,000

We would apply the periodic interest rate formula which is expressed as

P = a/[{(1+r)^n]-1}/{r(1+r)^n}]

Where

P represents the weekly payments.

a represents the amount that the company needs

r represents the rate.

n represents number of weekly payments. Therefore

a = 5,400000

There are 52 weeks in a year

r = 0.079/52 = 0.0015

n = 52 × 14 = 728

Therefore,

P = 5400000/[{(1+0.0015)^728]-1}/{0.0015(1+0.0015)^728}]

5400000/[{(1.0015)^728]-1}/{0.0015(1.0015)^728}]

P = 5400000/{2.98 -1}/[0.0015(2.98)]

P = 5400000/(1.98/0.00447)

P = 5400000/442.95

P = $12191

3 0

3 years ago

Solve |x| + 7 < 4. Please help

PilotLPTM [1.2K]

Answer:

no solution

Step-by-step explanation:

Subtract 7 from both sides of the inequality:

|x| +7 -7 < 4 -7

|x| < -3

This has <u>no solution</u>, because an absolute value cannot be negative.

4 0

4 years ago

Five more than a number is 25. What is this number?

Alexxx [7]

Answer:

5

Step-by-step explanation:

let the number be a.

5a=25

divide both sides by 5

5a=25

5divide by 5a is a.

5divided by 25 is 5

therefore,a=5.

the number is 5

5 0

3 years ago