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KonstantinChe [14]
2 years ago
12

The radius of a circle is changing at the rate of 1/π inches per second. At what rate, in square inches per second, is the circl

e’s area changing when the radius is 5 inches?
Mathematics
1 answer:
MAXImum [283]2 years ago
4 0

Answer:

10 square inches per second.

Step-by-step explanation:

The radius of the circle is given by the equation:

r(t) = (1/π  in/s)*t

Where time in seconds.

Remember that the area of a circle of radius R is written as:

A = π*R^2

Then the area of our circle will be:

A(t) = π*( (1/π  in/s)*t)^2 = π*(1/π  in/s)^2*(t)^2

Now we want to find the rate of change (the first derivation of the area) when the radius is equal to 5 inches.

Then the first thing we need to do is find the value of t such that the radius is equal to 5 inches.

r(t) = 5 in =  (1/  in/s)*t

       5in*(π s/in) = t

        5*π s = t

So the radius will be equal to 5 inches after 5*π seconds, let's remember that.

Now let's find the first derivate of A(t)

dA(t)/dt = A'(t) = 2*(π*(1/π  in/s)^2*t = (2*π*t)*(1/π  in/s)^2

Now we need to evaluate this in the time such that the radius is equal to 5 inches, we will get:

A'(5*π s) = (2*π*5*π s)*((1/π  in/s)^2

              = (10*π^2  s)*(1/π^2  in^2/s^2) = 10 in^2/s

The rate of change is 10 square inches per second.

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8 0
3 years ago
Find the inverse of the relation. Use proper notation. {(8,−1),(−8,−1),(−2,−8),(2,8)} please help!!
tiny-mole [99]

Answer: The inverse relation is { (-1, -8), (-1, -8), (-8, -2), (8, 2) }

The inverse is effectively the opposite of the original relation. It undoes what the original relation does. So we'll swap the x and y values for each given point in the form (x,y). Something like (8,-1) becomes (-1,8). The other points follow the same pattern as well.

6 0
2 years ago
Triangle VXW is similar to triangle ZXY. Triangle V X W. Side V W is 12 miles and side V X is 14 miles. Triangle Z X Y. Side Y Z
amid [387]

Answer: Kara should have written the proportion in step 1 as;

Start Fraction 12 Over 72 End Fraction = Start Fraction 14 Over x End Fraction (that is 12/72 = 14/x)

Step-by-step explanation: The two similar triangles are given with the following dimensions;

Triangle VXW with side VW = 12 and side VX = 14. Also Triangle ZXY with side YZ = 72 and side XZ = x.

For two triangles to be similar, then there must be a similarity ration that is consistent with all sides in both triangles. This means if in the first triangle a side measures  1 unit and the similar side in the other triangle measures 5 units, then the ratio of similarity of corresponding sides shall be ratio 1 : 5. So for every corresponding side in the second triangle the measurement shall be times five of the side that corresponds in the first triangle.

Therefore, in triangle VXW and triangle ZXY, the corresponding sides are as follows;

VX = ZX

VW = ZY

XW = XY

What Kara did was as follows;

VX/ZY = VW/ZX

Which translates to 14/72 = 12/x

This was a wrong calculation because the side that corresponds to VX is ZX and not ZY.

The correct step should therefore have been;

VW/ZY = VX/ZX

12/72 = 14/x (Step 1)

12x = (72) (14) {Step 2}

x = 1008/12 (Step 3)

x = 84 (Step 4)

5 0
3 years ago
Read 2 more answers
HELPPP
Rudiy27

Formula: A = 2wl + 2lh + 2hw

So... : A = 2(4x8) + 2(8x3) + 2(3x4)

         A = 2(32)   + 2(24)   + 2(12)

         A = 64 + 48 + 24

<u>Answer: A = 136</u> (add them all up)

Hope this helps!!!

:)

8 0
3 years ago
How can you estimate 74.3 divided by 8
Greeley [361]
The answer of 74 divided by 8 hope this helps
7 0
2 years ago
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