All categories

3 years ago

The area of a circle is 81pi in.squared. What is the circumference, in inches? Express your answer in terms of pi

Mathematics

2 answers:

Drupady [299]3 years ago

7 0

Answer:

18π

Step-by-step explanation:

the area of a circle is :

A= r²*π where r is the radius

here r² =81⇒ r= 9

the circumference of a circle is :

P= 2*r*π

P= 18π

Andrews [41]3 years ago

3 0

Answer:

18 pi inches

Step-by-step explanation:

The area of a circle is given by

A = pi r^2

81 pi = pi r^2

Divide by pi

81 = r^2

Take the square root of each side

sqrt(81) = sqrt (r^2)

9 = r

We want the circumference

C = 2 * pi * r

C = 2 * pi * 9

C = 18 pi

You might be interested in

2. Solve the system of equations. Write your answer in parametric vector notation. X, +5x2 + 4x3 + 3x4 +9xs = 18 2x, +6x2 + 4x3

ratelena [41]

Answer:

The system is inconsistent.

Step-by-step explanation:

The system is

$x_1+5x_2+4x_3+3x_4+9x_5=18\\2x_1+6x_2+4x_3+6x_4+6x_5=28\\3x_1+7x_2+4x_3+10x_4+x_5=41\\4x_1+6x_2+2x_3+7x_4+4x_5=29$

The associated matrix to the system is

$\left[\begin{array}{cccccc}1&5&4&3&9&18\\2&6&4&6&6&28\\3&7&4&10&1&41\\4&6&2&7&4&29\end{array}\right]$

Now we use row operations to find the echelon form of the matrix:

1. We substract to row 2, two times the row 1.

We substract to row 3, three times the row 1.

We substract to row 4, four times the row 1 and obtain the matrix

$\left[\begin{array}{cccccc}1&5&4&3&9&18\\0&-4&-4&0&-12&-8\\0&-8&-8&1&-26&-13\\0&-14&-14&-5&-32&-43\end{array}\right]$

2. We multiply the second row of the preview step by -1/4. We obtain the matrix

$\left[\begin{array}{cccccc}1&5&4&3&9&18\\0&1&1&0&3&2\\0&-8&-8&1&-26&-13\\0&-14&-14&-5&-32&-43\end{array}\right]$

We add to row 3, eight times the row 2.

We add to row 4, fourtheen times the row 2 and obtain the matrix

$\left[\begin{array}{cccccc}1&5&4&3&9&18\\0&1&1&0&3&2\\0&0&0&1&-2&3\\0&0&0&-5&10&-155\end{array}\right]$

4. We add to row 4 of the preview step, five times the row 3 and obtain the matrix

$\left[\begin{array}{cccccc}1&5&4&3&9&18\\0&1&1&0&3&2\\0&0&0&1&-2&3\\0&0&0&0&0&-140\end{array}\right]$

Using backward substitution we have that

$0x_5=-140$ , then $0=-140$ and this is absurd. Then The system is inconsistent.

4 0

3 years ago

What is the sum of -6 4/5 and 6 4/5

galben [10]

Answer:

Step-by-step explanation:

thanks for the points :)

4 0

3 years ago

If m ACB = 48° and m CAB = 47°, is line BC a tangent to circle A?

muminat

Answer: No, because ABC is not a right angle.

Step-by-step explanation: In triangle ABC, the three angles add up to 180

So angle B = 180 - 48 - 47 = 85.

7 0

3 years ago

~~~ 30 POINTS ~~~

trasher [3.6K]

1) 3x-2=x+10

Now, lets solve this step-by-step.

3x - 2 = x + 10
-x -x

3x - x = 2x 2x - 2 = 10

2x - 2 = 10
2x - 2+2 = 10+2 The inverse operation helps isolate the variable.

2x = 12

2x/2 = 12/2

x = 12/2
x = 6

Answer: x = 6

2) x + 4 = 19 - 2x 

We can solve this much faster

x + 4 = 19 - 2x
+2x

x+2x = 3x

3x + 4 = 19
-4 -4

19-4 = 15

3x= 15
3x/3 = 15/3
x= 5

Answer: x = 5

3) 8x - 20 = x + 15

Much faster now!!

8x - 20 = x + 15
-x
8x-x = 7x

7x - 20 = 15
+20 +20
15+20 = 35

7x = 35
7x/7 = 35/7
x = 35/7
x = 5

Answer: x= 5

3 0

3 years ago

Read 2 more answers

Raymond has a set of 57 toy cars and decides to sell 19 of them to Joey. About how many toy cars does Raymond have left

Dovator [93]

Answer:

raymond has about 38 cars left

Step-by-step explanation:

Because raymond started off with 57 cars and he got rid of( take away) 19 you must use subtraction. 57 - 19 =38

4 0

3 years ago