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stiks02 [169]
3 years ago
9

What is the equation of a circle centered at (1,-4) and a diameter 18?

Mathematics
2 answers:
hoa [83]3 years ago
7 0

Answer:

(x - 1)² + (y + 4)² = 81

Step-by-step explanation:

Circle Formula: (x - h)² + (y - k)² = r²

(h, k) is the center

2r = d

Step 1: Find <em>r</em>

18 = 2r

r = 9

Step 2: Plug known variables into formula

(x - 1)² + (y + 4)² = 9²

Step 3: Evaluate

(x - 1)² + (y + 4)² = 81

jonny [76]3 years ago
7 0

Answer:

(x-1)^2 + (y+4)^2 = 81

Step-by-step explanation:

The equation of a circle can be written as

(x-h)^2 + (y-k)^2 = r^2

where ( h,k) is the center and r is the radius

The center is ( 1,-4)

and the radius is d/2 = 18/2 = 9

(x-1)^2 + (y- -4)^2 = 9^2

(x-1)^2 + (y+4)^2 = 81

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The price of a watch was increased by 20% to £162. <br> What was the price before the increase?
Inessa [10]

Answer:

The answer is 135

Step-by-step explanation:

We can use formula: 162...120% since the price was increased by 20% which means it is 120%

So: 162...120%

x.... 100%

120x = 16200 => x = 135

4 0
3 years ago
How do you know if two lines are parallel without a equation?
sesenic [268]
If they do not have solutions (intersections).
If they do not have intersections then they must be parallel. Imagine it on the graph
7 0
3 years ago
The credit remaining on a phone card (in dollors) is a linear function of the total calling trime made with the card ( in minute
KATRIN_1 [288]

After 85 minutes of calls, there are $27.25 left on the card.

<h3>What is the remaining credit after 85 minutes of calls?</h3>

A linear equation in slope-intercept form is:

y = a*x + b

Where a is the slope.

If the line passes through two points (x₁, y₁) and (x₂, y₂) the slope is:

a = \frac{y_2 - y_1}{x_2 - x_1}

In this case, we know that the line passes through the points (22, 36.7) and (52, 32,20)

(points of the form (time, dollars)).

So the slope is:

a = \frac{32.2 - 36.7}{52 -22} = -0.15

The linear equation is then:

y = -0.15*x + b

To find the value of b, we use the point (22. 36.7)

36.7 = -0.15*22 + b

36.7 + 0.15*22 = b = 40

Then the linear equation is:

y = -0.15*x +40

The amount remaining in the credit card after 85 minutes is given by evaluating the above equation in x = 85.

y = -0.15*85 + 40 = 27.25

This means that after 85 minutes of calls, there are $27.25 left on the card.

If you want to learn more about linear equations:

brainly.com/question/1884491

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7 0
2 years ago
I don't know how to solve
Korolek [52]
The answer is 84 degrees you just subtract 180-90
4 0
3 years ago
1. If quadrilateral ABCD is rotated 270° clockwise about the origin, find the coordinates of B'.
Zielflug [23.3K]

Answer:

The coordinates of B' are (-3, 5).  

Step-by-step explanation:

For every 90 degrees rotated, the coordinate numbers switch and one is multiplied by -1, when clockwise it's the 2nd one, and when counterclockwise, it's the 1st.

4 0
3 years ago
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