The formula to calculate the z-score of a certain value is:
z = (x - (mean))/(standard deviation)
In this example, the x-value is 450, the S.D. is 100, and the mean is 500.
So, substitute these values into the formula.
z = (450-(500))/100
z=-50/100
z=-0.5
Therefore, the z-score is -0.5.
Angle a is 80, angle d is 100, angle c is 100
The radius of the given circle is 5 units with the equation x²+y²+8x-6y+21=0.
<h3>
What are circles?</h3>
All points in a plane that are at a certain distance from the center combine to form a circle.
It is the curve that a moving point in a plane draws to keep its distance from another point constant, to put it another way.
In the center of a circle, equal chords subtend equal angles.
So, the radius of the circle with equation x² + y² + 8x – 6y + 21 = 0:
General form:
(x – a)² + (y-b) = r²
x² + y² – 2ax – 2by + (a² + b² – r²) = 0
We know that: r = √(a² +b²)
Compare the following equation to the equation's general form.
We obtain:
-2ax = 8x ⇒ a = – 4
-2by = -6y ⇒ b = 3
r = √((-4)2 +32 ) = √16 + 9 = √25 = 5
Therefore, the radius of the given circle is 5 units with the equation x²+y²+8x–6y+21=0.
Know more about circles here:
brainly.com/question/24375372
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Correct question:
What is the radius of a circle whose equation is x² + y² + 8x – 6y + 21 = 0?
Answer:
A cube. It's like a die, each side has either 1, 2, 3, 4, 5, or 6