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3 years ago

AC=4, AE=7, AD=10, what is the length of AB? A: 1 3/7 B: 2 1/2 C: 5 5/7 D: 17 1/2

Mathematics

1 answer:

11Alexandr11 [23.1K]3 years ago

6 0

Answer:

C. $AB = 5\frac{5}{7}$

Step-by-step explanation:

When two polygons are considered similar, the ratio of their corresponding sides would also be equal.

Since ∆ABC and ∆ADE are similar, $\frac{AE}{AC} = \frac{AD}{AB}$

$\frac{7}{4} = \frac{10}{AB}$

Cross multiply

$7*AB = 10*4$

$7*AB = 40$

Divide both sides by 7 to find AB

$\frac{7*AB}{7} = \frac{40}{7}$

$AB = \frac{40}{7}$

$AB = 5\frac{5}{7}$

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If sin(x) = 5/13, and x is in quadrant 1, then tan(x/2) equals what?

Rufina [12.5K]

$x$ is in quadrant I, so $0$ , which means $0$ , so $\dfrac x2$ belongs to the same quadrant.

Now,

$\tan^2\dfrac x2=\dfrac{\sin^2\frac x2}{\cos^2\frac x2}=\dfrac{\frac{1-\cos x}2}{\frac{1+\cos x}2}=\dfrac{1-\cos x}{1+\cos x}$

Since $\sin x=\dfrac5{13}$ , it follows that

$\cos^2x=1-\sin^2x\implies \cos x=\pm\sqrt{1-\left(\dfrac5{13}\right)^2}=\pm\dfrac{12}{13}$

Since $x$ belongs to the first quadrant, you take the positive root ( $\cos x>0$ for $x$ in quadrant I). Then

$\tan\dfrac x2=\pm\sqrt{\dfrac{1-\frac{12}{13}}{1+\frac{12}{13}}}$

$\tan x$ is also positive for $x$ in quadrant I, so you take the positive root again. You're left with

$\tan\dfrac x2=\dfrac15$

4 0

3 years ago

we believe that 42% of freshmen do not visit their counselors regularly. For this year, you would like to obtain a new sample to

Maksim231197 [3]

Answer:

A sample of 1077 is required.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the zscore that has a pvalue of $1 - \frac{\alpha}{2}$ .

The margin of error is of:

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

42% of freshmen do not visit their counselors regularly.

This means that $\pi = 0.42$

98% confidence level

So $\alpha = 0.02$ , z is the value of Z that has a pvalue of $1 - \frac{0.02}{2} = 0.99$ , so $Z = 2.327$ .

How large of a sample size is required?

A sample size of n is required, and n is found when M = 0.035. So

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

$0.035 = 2.327\sqrt{\frac{0.42*0.58}{n}}$

$0.035\sqrt{n} = 2.327\sqrt{0.42*0.58}$

$\sqrt{n} = \frac{2.327\sqrt{0.42*0.58}}{0.035}$

$(\sqrt{n})^2 = (\frac{2.327\sqrt{0.42*0.58}}{0.035})^2$

$n = 1076.8$

Rounding up:

A sample of 1077 is required.

3 0

3 years ago

One root of f(x) = x + 10x2 – 25x – 250 is x = -10. What are all the roots of the function? Use the Remainder Theorem.

Natalka [10]

Answer:

-10

-5

Step-by-step explanation:

From the answers given, you probably mean f(x) = x^3 + 10x2 – 25x – 250

The Remainder Theorem is going to take a bit to solve.

You have to try the factors of 250. One way to make your life a lot easier is to graph the equation. That will give you the roots.

The graph appears below. Since the y intercept is -250 the graph goes down quite a bit and if you show the y intercept then it will not be easy to see the roots.

However just to get the roots, the graph shows that

x = -10

x = - 5

x = 5

The last answer is the right one. To use the remainder theorem, you could show none of the answers will give 0s except the last one. For example, the second one will give

f((10) = 10^3 + 10*10^2 - 25*10 - 250

f(10) = 1000 + 1000 - 250 - 250

f(10) = 2000 - 500

f(10) = 1500 which is not 0.

==================

f(1) = (1)^3 + 10*(1)^2 - 25(1) - 250

f(1) = 1 + 10 - 25 - 250

f(1) = -264 which again is not zero

3 0

3 years ago

Read 2 more answers

The product of a number and 9, increased by 4, is 58. Find the number.

diamong [38]

9x + 4 = 58
9x = 54
x = 6

The number is 6.

4 0

3 years ago

Which function does this graph represent: y=x-4;<br> y=-x+4;y=4x-1;y=-4x+1

allochka39001 [22]

The graph represents y=-4x-1

If you notice the line, it goes past the -1 on the y axis which indicates that the y intercept is -1 since that was the only choice which displayed this, we know that our answer is y=-4x-1

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3 years ago