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4 years ago

Circumference and Area of Circles

Mathematics

1 answer:

yanalaym [24]4 years ago

8 0

Step-by-step explanation:

Area of a circle = #r^2

1256 = 3.14 × r^2

r^2 = 1256/3.14

r^2 = 400

Square root of r = 20

Diameter = 2 × r = 2 × 20 = 40 inches

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In 2012, the population of a city was 6.27 million. The exponential growth rate was 1.47% per year.

Tcecarenko [31]

Answer:

a) $a(t)= 6.27e^{0.0147*t}$

b) 6.84 million

c) 2028.52

d) 47 years

Step-by-step explanation:

a)Here we know standard exponential growth rate is

$a(t)= ae^{k*t}$

In this put t=0 and a(t)=6.27 million

thus we get a = 6.27 million

now $\frac{da}{dt}=a(t)k$

this is equal to(in 2012)= $\frac{1.47}{100}*=0.0147$

b)Put t = 6

we get

$a(t)= 6.27e^{0.0147*6}$

=6.84 million

c) $8 = 6.27e^{0.0147*t}$

take log both sides

we get 16.52 years

d) $2*6.27=6.27e^{0.0147*t}$

take log both sides we get 47 years to get double the current population.

3 0

3 years ago

Sarah bought 6 2/3 yards of material. She used 3/4 of the material to make a costume for the school play. How much material did

Lelechka [254]

You’re full of cap don’t cap next time you’re capping the answer is 5/3

7 0

3 years ago

Solve -3 = x + x + x.

kozerog [31]

-3 = x + x + x
-3 = 3x
-3/3 = x
x = -1

6 0

3 years ago

Read 2 more answers

Lesson Check (4.MD.C.7)

vredina [299]

The measure of Zx is 4

8 0

3 years ago

Please answer question three and four if you can :)<br> Show full working out ty;)

nikklg [1K]

Step-by-step explanation:

Let D be the mid point of side BC, [B(2, - 1), C(5, 2)].

Therefore, by mid-point formula:

$D = ( \frac{2 + 5}{2}, \: \: \frac{ - 1 + 2}{2} ) = ( \frac{7}{2}, \: \: \frac{ 1}{2} ) \\ \therefore D= (3.5, \: \: 0.5) \\ \& \: A=(-1,\:\:4)...(given) \\\\ now \: by \: distance \: formula \\ \\ Length \: of \: segment \: AD \\ = \sqrt{( - 1 - 3.5)^{2} + {(4 - 0.5)}^{2} } \\ = \sqrt{(4.5)^{2} + {(3.5)}^{2} } \\ = \sqrt{20.25 + 12.25 } \\ = \sqrt{32.5} \\ \red{ \boxed{\therefore Length \: of \: segment \: AD = 5.7 \: units}}$

4 (a)

Equation of line AB[A(2, 1), B(-2, - 11)] in two point form is given as:

$\frac{y-y_1}{y_1-y_2} =\frac{x-x_1}{x_1 - x_2} \\\\\therefore \frac{y-1}{1-(-11)} =\frac{x-2}{2 - (-2) } \\\\\therefore \frac{y-1}{1+11} =\frac{x-2}{2 +2} \\\\\therefore \frac{y-1}{12} =\frac{x-2}{4} \\\\\therefore \frac{y-1}{3} =\frac{x-2}{1} \\\\\therefore y-1= 3(x - 2)\\\\\therefore y= 3x - 6+1\\\\\therefore y= 3x - 5\\\\ \huge \purple {\boxed {\therefore 3x - y-5=0}} \\$

is the equation of line AB.

Now we have to check whether C(4, 7) lie on line AB or not.

Let us substitute x = 4 & y = 7 on the Left hand side of equation of line AB and if it gives us 0, then C lies on the line.

$LHS = 3x - y-5\\=3\times 4-7-5\\= 12-12\\=0\\= RHS$

Hence, point C (4, 7) lie on the straight line AB.

4(b)

Like we did in 4(a), first find the equation of line AB and then substitute the coordinates of point C in equation and if they satisfy the equation, then all the three points lie on the straight line.

4 0

4 years ago