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zysi [14]
3 years ago
11

What is the directrix of a parabola with focus (4,-1) and a vertex at (4,-5)?​

Mathematics
1 answer:
elena-s [515]3 years ago
5 0

Answer:

<h3>                 y = -9</h3>

Step-by-step explanation:

The directrix is at the same distance from the vertex as the focus but on the opposite side of the vertex.

x coordinate the same for a focus and a vertex (4) means the parabola opens up or down and the directrix is parallel to the x-axis.

y coordinate of the focus greater than y coordinate of the vertex means the parabola opens up and the directrix lays below the vertex.

-1-(-5) = - 1 + 5 = 4

so: - 5 - 4 = -9 is the y coordinate of points of the directrix

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aev [14]

The above question is not complete because it was not written and arranged properly

Complete Question

1) A cone has a diameter of 8 units and a height of 8 units. Its radius is 4 units, and its volume is ______ cubic units.

2) A cylinder with the same height and radius as the cone will have a volume ______ of cubic units.

3) If a sphere has the same radius as the cylinder, its volume is ______the volume of the cylinder. Answer: 1) Volume of the cone = 134.04cubic units

2)Volume of the cylinder = 402.12cubic units

3) Volume of the sphere= 268.08 cubic units. Hence, if a sphere has the same radius as the cylinder, its volume is 2/3 times the volume of the cylinder.

Step-by-step explanation:

1) A cone has a diameter of 8 units and a height of 8 units. Its radius is 4 units, and its volume is ______ cubic units.

Volume of a cone = 1/3πr²h

h = 8 units

r = 4 units

Volume = 1/3 × π × 4² × 8

134.04cubic units

2) A cylinder with the same height and radius as the cone will have a volume ______ of cubic units.

Volume of a cylinder = πr²h

Height and radius is the same as that of the cones hence,

h = 8 units

r = 4 units

= π × 4² × 8

= 402.12cubic units.

3) If a sphere has the same radius as the cylinder, its volume is ______the volume of the cylinder.

Volume of a Sphere = 4/3πr³

r = radius of the cylinder = 4 units

Volume of a Sphere = 4/3 × π × 4³

= 268.08 cubic units.

From the above question, we are asked to compare the volume of the sphere with the volume of the cylinder

Volume of the sphere : Volume of the cylinder

268.08 cubic units : 402.12 cubic units

268.08/402.12 = 2/3

Therefore, the volume of the sphere is 2/3 times the volume of the cylinder

6 0
2 years ago
the table shows the ratio between the number of books ordered and their cost. 7,14 8,16 9,18. find equivalent ratios when the nu
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Answer:

Number of Books. Cost (dollars). 7 14. 8 16. 9 18. Find equivalent ratios when the number of books ordered is 1, 2, and 3. Write them as ordered pairs in the form...

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3 years ago
Right the slope intercept of the equation of the line through the given point with the given slope through (2, 1) slope = 5/2 m=
solmaris [256]
M = 5/2
B = -4
Y - 1 = 5/2(x - 2)
Y - 1 = 5/2x - 5
+1. +1
Y = 5/2x - 4

(I think)
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3 years ago
The drama club is selling tickets to their play to raise money for the show's expenses. Each student ticket sells for $4 and eac
ki77a [65]

Answer:

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Step-by-step explanation:

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To fine how much money they earn you will just have to add them up so

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3 years ago
Complete the factored form of the algebraic expression <br> 18a + 3 = 3 ( + )
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Answer: 0

Step-by-step explanation: 18a + 3 = 3

                                                     -3    -3

                                                   --------------

                                              18a   =    0  you can't divide 18 and zero it would be 0

8 0
3 years ago
Read 2 more answers
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