Answer:
Lisa must get an 88.75 or higher to stay in between 80 and 90.
Step-by-step explanation:
Answer:
(x + 4)^2 + (y - 8)^2 = 81
or
(x + 4)^2 + (y - 8)^2 = 9^2 depending on how your teacher wants it written.
Step-by-step explanation:
The standard form for a circle is
(x + h)^2 + (y + k)^2 = r^2
r is the radius.
You are given the diameter
r = d/2
r = 18/2
r = 9
So you already have the right hand side of the equation
(x + h)^2 + (y + k)^2 = 9*2
(x + h)^2 + (y + k)^2 = 81
You basically have h and k as well. They come from the center point.
h = 4
k = - 8
So the equation of the circle (and the answer) is
(x + 4)^2 + (y - 8)^2 = 81
One question remains. Why do the x and y values change signs? If you know what the distance formula is, then what you are finding is the distance r of all points on the circle from the center of the circle.
It is the distance formula that is actually the formula for the circle.
If you would like to solve the equation k / 2 + 9 = 30, you can calculate this using the following steps:
k / 2 + 9 = 30
k / 2 = 30 - 9
k / 2 = 21 /*2
k = 21 * 2
k = 42
The result is 42.
Answer:
6
Step-by-step explanation:
sorry if it wrong