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2 years ago

Geometry Question find the area of the circle to the nearest hundredth.

Mathematics

1 answer:

Nana76 [90]2 years ago

4 0

Formula for the area of a circle: A = πr²

π is approximately 3.14

Solve for the area:

A = (3.14)(8.6)²

A = (3.14)(73.96) or 73.96π

A = 232.2344

Round to the nearest hundredth:

232.2344 → 232.23

Therefore, the area of the circle is 232.23cm² or 73.96π cm²

Best of Luck!

You might be interested in

What are the factors of the polynomial function? Use the rational root theorem to determine the factors. f(x) = 2x³ + x² - 8x -

fredd [130]

Answer:

( x + 2 ) ( x - 2 ) ( 2x + 1)

Step-by-step explanation:

coefficient of x³ is 2 and denote it with q and denote -4 as p

the set of possible rational roots through rational theorem will be within ± (p/q)

now factors of -4 are ±(1,2,4) and factors of 2 are ± (1,2) the possible rational roots are ± ( 1/1, 1/2, 2/1, 2/2, 4/1, 4/2) which reduces to ± (1, 1/2, 2, 4)

substitute each of the value into the equation

f(x) = 2x³ + x² - 8x - 4 to the root ( that gives f(x) = 0)

the equation can be made easy writing it in reduced form

2x³ + x² - 8x - 4

(2x³ + x²) - (8x + 4)

x² (2x + 1) - 4 (2x + 1)

(x² - 4) (2x + 1)

( x + 2 ) ( x - 2) ( 2x + 1) are the factors which correspond to 2, -2, -1/2 roots

4 0

2 years ago

The center of a circle is at the origin on a coordinate grid. The vertex of a parabola that opens upward is at (0, 9). If the ci

zhannawk [14.2K]

Answer:

"The maximum number of solutions is one."

Step-by-step explanation:

Hopefully the drawing helps visualize the problem.

The circle has a radius of 9 because the vertex is 9 units above the center of the circle.

The circle the parabola intersect only once and cannot intercept more than once.

The solution is "The maximum number of solutions is one."

Let's see if we can find an algebraic way:

The equation for the circle given as we know from the problem without further analysis is so far $x^2+y^2=r^2$ .

The equation for the parabola without further analysis is $y=ax^2+9$ .

We are going to plug $ax^2+9$ into $x^2+y^2=r^2$ for $y$ .

$x^2+y^2=r^2$

$x^2+(ax^2+9)^2=r^2$

To expand $(ax^2+9)^2$ , I'm going to use the following formula:

$(u+v)^2=u^2+2uv+v^2$ .

$(ax^2+9)^2=a^2x^4+18ax^2+81$ .

$x^2+y^2=r^2$

$x^2+(ax^2+9)^2=r^2$

$x^2+a^2x^4+18ax^2+81=r^2$

So this is a quadratic in terms of $x^2$

Let's put everything to one side.

Subtract $r^2$ on both sides.

$x^2+a^2x^4+18ax^2+81-r^2=0$

Reorder in standard form in terms of x:

$a^2x^4+(18a+1)x^2+(81-r^2)=0$

The discriminant of the left hand side will tell us how many solutions we will have to the equation in terms of $x^2$ .

The discriminant is $B^2-4AC$ .

If you compare our equation to $Au^2+Bu+C$ , you should determine $A=a^2$

$B=(18a+1)$

$C=(81-r^2)$

The discriminant is

$B^2-4AC$

$(18a+1)^2-4(a^2)(81-r^2)$

Multiply the (18a+1)^2 out using the formula I mentioned earlier which was:

$(u+v)^2=u^2+2uv+v^2$

$(324a^2+36a+1)-4a^2(81-r^2)$

Distribute the 4a^2 to the terms in the ( ) next to it:

$324a^2+36a+1-324a^2+4a^2r^2$

$36a+1+4a^2r^2$

We know that $a>0$ because the parabola is open up.

We know that $r>0$ because in order it to be a circle a radius has to exist.

So our discriminat is positive which means we have two solutions for $x^2$ .

But how many do we have for just $x$ .

We have to go further to see.

So the quadratic formula is:

$\frac{-B \pm \sqrt{B^2-4AC}}{2A}$

We already have $B^2-4AC}$

$\frac{-(18a+1) \pm \sqrt{36a+1+4a^2r^2}}{2a^2}$

This is t he solution for $x^2$ .

To find $x$ we must square root both sides.

$x=\pm \sqrt{\frac{-(18a+1) \pm \sqrt{36a+1+4a^2r^2}}{2a^2}}$

So there is only that one real solution (it actually includes 2 because of the plus or minus outside) here for x since the other one is square root of a negative number.

That is,

$x=\pm \sqrt{\frac{-(18a+1) \pm \sqrt{36a+1+4a^2r^2}}{2a^2}}$

means you have:

$x=\pm \sqrt{\frac{-(18a+1)+\sqrt{36a+1+4a^2r^2}}{2a^2}}$

$x=\pm \sqrt{\frac{-(18a+1)-\sqrt{36a+1+4a^2r^2}}{2a^2}}$ .

The second one is definitely includes a negative result in the square root.

18a+1 is positive since a is positive so -(18a+1) is negative

2a^2 is positive (a is not 0).

So you have (negative number-positive number)/positive which is a negative since the top is negative and you are dividing by a positive.

We have confirmed are max of one solution algebraically. (It is definitely not 3 solutions.)

If r=9, then there is one solution.

If r>9, then there is two solutions as this shows:

$x=\pm \sqrt{\frac{-(18a+1)+\sqrt{36a+1+4a^2r^2}}{2a^2}}$

r=9 since our circle intersects the parabola at (0,9).

Also if (0,9) is intersection, then

$0^2+9^2=r^2$ which implies r=9.

Plugging in 9 for r we get:

$x=\pm \sqrt{\frac{-(18a+1)+\sqrt{36a+1+4a^2(9)^2}}{2a^2}}$

$x=\pm \sqrt{\frac{-(18a+1)+\sqrt{36a+1+324a^2}}{2a^2}}$

$x=\pm \sqrt{\frac{-(18a+1)+\sqrt{(18a+1)^2}}{2a^2}}$

$x=\pm \sqrt{\frac{-(18a+1)+18a+1}{2a^2}}$

$x=\pm \sqrt{\frac{0}{2a^2}}$

$x=\pm 0$

$x=0$

The equations intersect at x=0. Plugging into $y=ax^2+9$ we do get $y=a(0)^2+9=9$ .

After this confirmation it would be interesting to see what happens with assume algebraically the solution should be (0,9).

This means we should have got x=0.

$0=\frac{-(18a+1)+\sqrt{36a+1+4a^2r^2}}{2a^2}$

A fraction is only 0 when it's top is 0.

$0=-(18a+1)+\sqrt{36a+1+4a^2r^2}$

Add 18a+1 on both sides:

$18a+1=\sqrt{36a+1+4a^2r^2$

Square both sides:

$324a^2+36a+1=36a+1+4a^2r^2$

Subtract 36a and 1 on both sides:

$324a^2=4a^2r^2$

Divide both sides by $4a^2$ :

$81=r^2$

Square root both sides:

$9=r$

The radius is 9 as we stated earlier.

Let's go through the radius choices.

If the radius of the circle with center (0,0) is less than 9 then the circle wouldn't intersect the parabola. So It definitely couldn't be the last two choices.

7 0

2 years ago

Read 2 more answers

The pizza has an area of 78.5 in². What is the minimum width of a placemat that can be placed underneath it so that the pizza do

xz_007 [3.2K]

Answer:

The minimum width of the placemat is 10 inches.

Step-by-step explanation:

Let suppose that placemat has a square form, whose width must be at least equal to the diameter of the pizza, so that pizza does not touch the table. Hence, the following relationship is obtained:

$w = D$

Where:

$w$ - Width of the placemat, measured in inches.

$D$ - Diameter of pizza, measured in inches.

The area of the pizza, measured in square inches, is determined by this formula:

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

The diameter is cleared afterwards:

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

If $A = 78.5\,in^{2}$ and $\pi = 3.14$ , then:

$D = \sqrt{\frac{4\cdot (78.5\,in^{2})}{3.14} }$

$D = 10\,in$

The minimum width of the placemat is 10 inches.

4 0

2 years ago

Read 2 more answers

As part of a community service project at your high school, you are organizing a fund-raiser at the neighborhood movie theater.

kirill115 [55]

So the questions ask to write an equations that shows how much money will be donated and then solve. So let Y be the amount of money and X will be the number of people attending. So the equation would be y=(10-5.5)X so the answer would be Y=2250. I hope you are satisfied with my answer and feel free to ask for more

8 0

2 years ago

Read 2 more answers

Pls explain your work!

mylen [45]

Answer:

find total volume to find what amount is 20%

hack, is put the 20% in alreadyy to find 20% volume

20%=1/5

vcone=1/3(hpir^2)

times thath by 1/5

vcone=1/15(hpir^2)

d/2=r

given

4.8=d

4.8/2=d/2=r=2.4

10=h

V=1/15(10pi2.4^2)

V=1/15(10pi5.76)

V=1/15(57.6pi)

V=3.84pi

V=12.0637 cubic inches=20% of vase

0.5 cubc inches per min

0.5 times t=12.0637

divide both sides by 0.5

t=24.1237

about 24 minutes

Step-by-step explanation:

6 0

2 years ago