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3 years ago

The radius of a circle is 4 feet. What is the circle's circumference?Use 3.14 for r=4 ft

Mathematics

1 answer:

Lady_Fox [76]3 years ago

5 0

Answer:

50.24 is the circumfrence

If we were to use actual pi the answer would be -

50.26548246

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Find the vertices and foci of the hyperbola. 9x2 − y2 − 36x − 4y + 23 = 0

Xelga [282]

Hey there, hope I can help!

NOTE: Look at the image/images for useful tips
$\left(h+c,\:k\right),\:\left(h-c,\:k\right)$

$\frac{\left(x-h\right)^2}{a^2}-\frac{\left(y-k\right)^2}{b^2}=1\:\mathrm{\:is\:the\:standard\:equation\:for\:a\:right-left\:facing:H}$
with the center of (h, k), semi-axis a and semi-conjugate - axis b.
NOTE: H = hyperbola

$9x^2-y^2-36x-4y+23=0 \ \textgreater \ \mathrm{Subtract\:}23\mathrm{\:from\:both\:sides}$
$9x^2-36x-4y-y^2=-23$

$\mathrm{Factor\:out\:coefficient\:of\:square\:terms}$
$9\left(x^2-4x\right)-\left(y^2+4y\right)=-23$

$\mathrm{Divide\:by\:coefficient\:of\:square\:terms:\:}9$
$\left(x^2-4x\right)-\frac{1}{9}\left(y^2+4y\right)=-\frac{23}{9}$

$\mathrm{Divide\:by\:coefficient\:of\:square\:terms:\:}1$
$\frac{1}{1}\left(x^2-4x\right)-\frac{1}{9}\left(y^2+4y\right)=-\frac{23}{9}$

$\mathrm{Convert}\:x\:\mathrm{to\:square\:form}$
$\frac{1}{1}\left(x^2-4x+4\right)-\frac{1}{9}\left(y^2+4y\right)=-\frac{23}{9}+\frac{1}{1}\left(4\right)$

$\mathrm{Convert\:to\:square\:form}$
$\frac{1}{1}\left(x-2\right)^2-\frac{1}{9}\left(y^2+4y\right)=-\frac{23}{9}+\frac{1}{1}\left(4\right)$

$\mathrm{Convert}\:y\:\mathrm{to\:square\:form}$
$\frac{1}{1}\left(x-2\right)^2-\frac{1}{9}\left(y^2+4y+4\right)=-\frac{23}{9}+\frac{1}{1}\left(4\right)-\frac{1}{9}\left(4\right)$

$\mathrm{Convert\:to\:square\:form}$
$\frac{1}{1}\left(x-2\right)^2-\frac{1}{9}\left(y+2\right)^2=-\frac{23}{9}+\frac{1}{1}\left(4\right)-\frac{1}{9}\left(4\right)$

$\mathrm{Refine\:}-\frac{23}{9}+\frac{1}{1}\left(4\right)-\frac{1}{9}\left(4\right) \ \textgreater \ \frac{1}{1}\left(x-2\right)^2-\frac{1}{9}\left(y+2\right)^2=1 \ \textgreater \ Refine$
$\frac{\left(x-2\right)^2}{1}-\frac{\left(y+2\right)^2}{9}=1$

Now rewrite in hyperbola standardform
$\frac{\left(x-2\right)^2}{1^2}-\frac{\left(y-\left(-2\right)\right)^2}{3^2}=1$

$\mathrm{Therefore\:Hyperbola\:properties\:are:}\left(h,\:k\right)=\left(2,\:-2\right),\:a=1,\:b=3$
$\left(2+c,\:-2\right),\:\left(2-c,\:-2\right)$

Now we must compute c
$\sqrt{1^2+3^2} \ \textgreater \ \mathrm{Apply\:rule}\:1^a=1 \ \textgreater \ 1^2 = 1 \ \textgreater \ \sqrt{1+3^2}$

$3^2 = 9 \ \textgreater \ \sqrt{1+9} \ \textgreater \ \sqrt{10}$

Therefore the hyperbola foci is at $\left(2+\sqrt{10},\:-2\right),\:\left(2-\sqrt{10},\:-2\right)$

For the vertices we have $\left(2+1,\:-2\right),\:\left(2-1,\:-2\right)$

Simply refine it
$\left(3,\:-2\right),\:\left(1,\:-2\right)$
Therefore the listed coordinates above are our vertices

Hope this helps!

8 0

4 years ago

A freight train starts from Los Angeles and heads for Chicago at 40 mph. Two hours later, a passenger train leaves the same stat

Degger [83]

I'm going to assume that they are on parallel tracks, and not the same track.

60x=40(x+2)

60x=40x+80

20x=80

x=4

You can check the work I've provided by filling in the answer for x into the initial question.

ʕ·ᴥ·ʔ

3 0

3 years ago

There are 48 DVDs of comedies and dramas on the shelf. If 25% of the DVDs are comedies, how many are dramas?

Mazyrski [523]

There are 36 drama DVD's

<em><u>Solution:</u></em>

Given that there are 48 DVD's of comedies and dramas on shelf

25 % of DVD's are comedies

To find: number of drama DVD's

Total number of dvd = 48

Number of comedy dvd = 25 % of 48

Let us find 25 % of 48

$\rightarrow 25 \% \text{ of } 48\\\\\rightarrow 25 \% \times 48\\\\\rightarrow \frac{25}{100} \times 48\\\\\rightarrow 0.25 \times 48 = 12$

Thus, number of comedy dvd = 12

Thus we get,

number of drama DVD's = Total number of dvd - number of comedy dvd

number of drama dvd = 48 - 12 = 36

Thus there are 36 drama dvd's

4 0

3 years ago

What is pythagoras theorem

Alborosie

Answer:

hypotenuse²=base²x height²

Step-by-step explanation:

It is used to find the third side of a triangle.

Hope it helps :)

6 0

3 years ago

PLS HELP ME ASAP FOR 39 (SHOW WORK!) + LOTS OF POINTS!! *CORRECT ANSWER ONLY!*

Nady [450]

The straight line ON has the following equation :
(x - 18)/(x - 0) = (y - 12)/(y - 0)
Where (18,12) are coordinates of N and (0,0) are coordinates of O.
x - 18/x = y - 12/y
-18y = - 12x
y =12x/18 - - - - - (a)

The coordinates satisfy equation (a) are (7.5, 5)

Therefore D is the correct answer.

Good luck

7 0

3 years ago

Read 2 more answers