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3 years ago

A = 1 4 π d 2 what is the formula to calculate the diameter of a circle

Mathematics

1 answer:

Anestetic [448]3 years ago

3 0

Answer:

$D=2\sqrt{\frac{A}{\pi}}$

Step-by-step explanation:

we know that

The area of the circle is equal to

$A=\frac{1}{4}\pi D^{2}$

where

D is the diameter of the circle

Solve for D

That means-----> Isolate the variable D

Multiply both sides by 4 to remove the fraction

$4A=\pi D^{2}$

Divide both sides by π

$\frac{4A}{\pi}=D^2$

square root both sides

$\sqrt{\frac{4A}{\pi}}=D$

Rewrite

$D=\sqrt{\frac{4A}{\pi}}$

Simplify

$D=2\sqrt{\frac{A}{\pi}}$

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Jose bought 1.5 pounds of apples for $3.60.

ipn [44]

I think the answer would be 81.60

8 0

3 years ago

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The sum of first three terms of a finite geometric series is -7/10 and their product is -1/125. [Hint: Use a/r, a, and ar to rep

Alchen [17]

Ooh, fun

geometric sequences can be represented as
$a_n=a(r)^{n-1}$
so the first 3 terms are
$a_1=a$
$a_2=a(r)$
$a_2=a(r)^2$

the sum is -7/10
$\frac{-7}{10}=a+ar+ar^2$
and their product is -1/125
$\frac{-1}{125}=(a)(ar)(ar^2)=a^3r^3=(ar)^3$

from the 2nd equation we can take the cube root of both sides to get
$\frac{-1}{5}=ar$
note that a=ar/r and ar²=(ar)r
so now rewrite 1st equation as
$\frac{-7}{10}=\frac{ar}{r}+ar+(ar)r$
subsituting -1/5 for ar
$\frac{-7}{10}=\frac{\frac{-1}{5}}{r}+\frac{-1}{5}+(\frac{-1}{5})r$
which simplifies to
$\frac{-7}{10}=\frac{-1}{5r}+\frac{-1}{5}+\frac{-r}{5}$
multiply both sides by 10r
-7r=-2-2r-2r²
add (2r²+2r+2) to both sides
2r²-5r+2=0
solve using quadratic formula
for $ax^2+bx+c=0$
$x=\frac{-b \pm \sqrt{b^2-4ac}}{2a}$
so
for 2r²-5r+2=0
a=2
b=-5
c=2

$r=\frac{-(-5) \pm \sqrt{(-5)^2-4(2)(2)}}{2(2)}$
$r=\frac{5 \pm \sqrt{25-16}}{4}$
$r=\frac{5 \pm \sqrt{9}}{4}$
$r=\frac{5 \pm 3}{4}$
so
$r=\frac{5+3}{4}=\frac{8}{4}=2$ or $r=\frac{5-3}{4}=\frac{2}{4}=\frac{1}{2}$

use them to solve for the value of a
$\frac{-1}{5}=ar$
$\frac{-1}{5r}=a$
try for r=2 and 1/2
$a=\frac{-1}{10}$ or $a=\frac{-2}{5}$

test each
for a=-1/10 and r=2
a+ar+ar²= $\frac{-1}{10}+\frac{-2}{10}+\frac{-4}{10}=\frac{-7}{10}$
it works

for a=-2/5 and r=1/2
a+ar+ar²= $\frac{-2}{5}+\frac{-1}{5}+\frac{-1}{10}=\frac{-7}{10}$
it works

both have the same terms but one is simplified

the 3 numbers are $\frac{-2}{5}$ , $\frac{-1}{5}$ , and $\frac{-1}{10}$

6 0

3 years ago

A bag contains 5 red, 6 green, 7 yellow, and 8 blue jelly beans. A jelly bean is selected at random. What is the probability tha

Slav-nsk [51]

Answer:

4/13 is the probability does a blue Jelly Bean is selected

Step-by-step explanation:

sample space = sum of all the jelly beans in the bag

sample space =5+6+7+8

sample space =26

probability = Jelly Bean selected / sample space

probability =8/26

probability =4/13

4 0

3 years ago

Pls help i will give brainliest

Novosadov [1.4K]

<h3>Answer: -a > -b</h3>

Explanation:

Let's go over an example.

We'll have a = 1 and b = 7 which makes a < b true. Feel free to pick your own favorite pair of numbers such that b is larger than 'a'.

The corresponding opposites are: -a = -1 and -b = -7

The relationship flips because the opposites of each number are flipped. So instead of saying -a < -b, we have -a > -b

Sure enough, -1 > -7 is a true statement. Use a number line to see this. I recommend a vertical number line.

In short, going from a < b to -a > -b means we flip the signs of each term, and we flip the inequality sign as well.

4 0

2 years ago

The CP of 25 articles is equal to the SP of 30 articles . Find the profit and loss percentage .

Studentka2010 [4]

Answer:

Loss = 16.67%

Step-by-step explanation:

Assume cost price(CP) of 1 article = x

Therefore cost price of 25 articles = 25x

Given cost price of 25 article = selling price of 30 articles

Clearly, it is a loss.

Selling price(SP) of 30 articles = 25x

$So , \ selling \ price\ of\ one\ article = \frac{25x}{30}\\\\Therefore , Loss \% = \frac{CP - SP}{CP} \times 100\\$

$=\frac{x - \frac{25x}{30}}{x } \times 100\\\\=\frac{30x - 25x }{30x }\times 100\\\\=\frac{5}{30} \times 100\\\\=16.67 \%$

5 0

3 years ago

Read 2 more answers