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3 years ago

Find the area of a circle with the circumference 18(pi)

Mathematics

2 answers:

jek_recluse [69]3 years ago

8 0

Circumference = $2\pi r$

$\frac{18\pi}{2\pi} = \frac{2\pi r }{2\pi }$

18 ÷ 2 = 9

r = 9

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Area = $\pi r^{2}$

= $\pi (9)^{2}$

= 81 $\pi$ units².

JulsSmile [24]3 years ago

5 0

Answer:

D 81 pi units^2

Step-by-step explanation:

The circumference of a circle is given by

C = 2 * pi *r

18 pi = 2 * pi *r

Divide each side by 2 * pi

18 pi / (2 pi) = 2 pi * r/ (2 pi)

9 = r

Now we can find the area. Area is given by

A = pi r^2

A = pi * 9^2

A = 81 pi units^2

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A certain television is advertised as a 55-inch TV (the diagonal length). If the width of the TV is 42 inches, how many inches t

Mumz [18]

Answer:

69.20in

Step-by-step explanation:

Given data

diagonal of the TV d= 55in

Widht of the TV w= 42 in

Hight h= ???

Applying the Pythagoras theorem

d^2= w^2+ h^2

substitute

55^2= 42^2+ h^2

3025= 1764+ h^2

3025+1764= h^2

4789= h^2

h=√4789

h= 69.20

Hence the Heigth is 69.20in

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3 years ago

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Vikki [24]

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3 years ago

Given the matrices: 1 2 A= 1 -1 2 1 1 B= 3 4 Calculate AB: C11 C12 [2.1] х 1 2 3 4 C21 C22 C11 = C12 = -2 C22 - C215 DONE

eduard

Answer:

$\:c_{11}=-2,\:\:\:c_{12}=-2$

$\:c_{21}=5,\:\:\:c_{22}=8$

Step-by-step explanation:

Given the matrices

$A=\begin{pmatrix}1&-1\\ 2&1\end{pmatrix}$

$B=\begin{pmatrix}1&2\\ \:3&4\end{pmatrix}$

Calculating AB:

$\begin{pmatrix}1&-1\\ \:\:2&1\end{pmatrix}\times \:\begin{pmatrix}1&2\\ \:\:3&4\end{pmatrix}=\begin{pmatrix}c_{11}&c_{12}\\ \:\:\:c_{21}&c_{22}\end{pmatrix}$

Multiply the rows of the first matrix by the columns of the second matrix

$=\begin{pmatrix}1\cdot \:1+\left(-1\right)\cdot \:3&1\cdot \:2+\left(-1\right)\cdot \:4\\ 2\cdot \:1+1\cdot \:3&2\cdot \:2+1\cdot \:4\end{pmatrix}$

$=\begin{pmatrix}-2&-2\\ 5&8\end{pmatrix}$

Hence,

$\begin{pmatrix}c_{11}&c_{12}\\ \:\:\:c_{21}&c_{22}\end{pmatrix}=\begin{pmatrix}-2&-2\\ \:5&8\end{pmatrix}$

Therefore,

$\:c_{11}=-2,\:\:\:c_{12}=-2$

$\:c_{21}=5,\:\:\:c_{22}=8$

5 0

3 years ago

Read 2 more answers

Solve by completing the square. x2^+8x= -20

Schach [20]

Step-by-step explanation:

x2^+8x=-20

9x^2=20

x^2=20-9

x^2=11

√x^2=√11

x=√11

3 0

3 years ago

On one side of the balance scale, Henry placed a 6-gram weight. On the other side of the scale, he placed a ballet slipper.

olchik [2.2K]

Answer:

A. 6,000 miligrams

Explanation:

A balance scale is balanced when the weights on both sides are equal. Then, since the image shows that both sides are equal, the weight of the 6-gram weight, placed by Henry on one side of the balance scale is equal to the weight of the ballet slipper placed on the other side.

Weight of the balance slipper = weight of the 6-gram weight

Weight of the balance slipper = 6 grams

Conversion of units:

6 grams × 1,000miligrams/1gram = 6,000 miligrams

Weight of the balance slipper = 6,000 miligrams

That is the option A.

7 0

3 years ago