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Radda [10]
2 years ago
7

How do you do this??

Mathematics
2 answers:
lisabon 2012 [21]2 years ago
8 0

Answer:

131.964 cm

Step-by-step explanation:

C = 2 \pi r = 2 * 3.142 * 21 = 3.142 * 42 = 131.964 \ cm

Alex777 [14]2 years ago
6 0

The formula for the circumference of a circle = 2 x radius x pi

The radius is given as 21 cm and pi = 3.142

Circumference = 2 x 21 x 3.142 = 131.964 cm

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The focus of a parabola is (0, -3) and the directrix is y = 3. What is the equation of the parabola?
OleMash [197]

Answer:

The equation of the parabola is y = -12\cdot x^{2}.

Step-by-step explanation:

Since the directrix is of the form y = a, the parabola is vertical. The vertex of the parabola (V(x,y)) is the midpoint between the focus (F(x,y)) and a point of the directrix (P(x,y)), that is to say:

V(x,y) = \frac{1}{2}\cdot F(x,y) + \frac{1}{2}\cdot P(x,y) (1)

If we know that F(x,y) = (0, -3) and P(x,y) = (0, 3), then the coordinates of the vertex of the parabola:

V(x,y) = \frac{1}{2}\cdot (0, -3) + \frac{1}{2}\cdot (0, 3)

V(x,y) = (0, 0)

The vertex factor (p) is the distance of the focus with respect to the vertex:

p = \sqrt{[F(x,y)-V(x,y)]\,\bullet \,[F(x,y)-V(x,y)]} (2)

If we know that F(x,y) = (0, -3) and V(x,y) = (0, 0), then the vertex factor is:

p = \sqrt{0^{2}+(-3)^{2}}

p = -3

The equation of the parabola in the vertex form is described below:

y - k = 4\cdot p \cdot (x-h)^{2} (3)

Where:

x - Independent variable.

y - Dependent variable.

h, k - Coordinates of the vertex.

If we know that (h,k) = (0, 0) and p = -3, then the equation of the parabola is y = -12\cdot x^{2}.

6 0
2 years ago
Use a model to divide. 1/2÷7 . What is the answer 2/7 1/14 14 3 1/2?
shutvik [7]

Answer:

1/14 i think

Step-by-step explanation:

7 0
3 years ago
5 divided by 978 with remainder
grigory [225]

Hi!

978 can't go into 5 at all, so the answer is 0 R: 978

Hope this helps! :)

-Peredhel

6 0
3 years ago
Read 2 more answers
The answer to this question is C) 7
Sedbober [7]

Answer:

the answer is C)7                                        

3 0
2 years ago
ASAP PLZZZ The axis of symmetry for the graph of the function f start bracket x end bracket equals one-quarter x square plus b x
Lilit [14]

Answer:

b=-3

Step-by-step explanation:

The  given function is f(x)=\frac{1}{4}x^2+bx+10.

When we compare to ax^2+bx+=0, we have

a=\frac{1}{4} and c=10

The equation of the axis of symmetry of a vertical parabola is:

x=-\frac{b}{2a}

Also from the question the axis of symmetry is x=6

We substitute the values to get:

6=-\frac{b}{2*\frac{1}{4}}

6=-\frac{b}{\frac{1}{2}}

b=-\frac{1}{2}*6

b=-3

7 0
3 years ago
Read 2 more answers
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