Points: (2, -3) and (-2, 0)
Slope: -3/4
Equation: y = -0.75x-1.5
It is (x + 2)^2 + (y - 1)^2 = 4
It is (x + 2)^2 + (y + 3)^2 = 9
Diameter.
A straight line passing from side to side going through the middle of a circle or sphere is a diameter.
If you mean a center of (3, 10) passing through (12, 12) then the radius is the square root of 85 which is about 9.2195 rounded to four decimal places.
a diameter
It is (x + 2)^2 + (y - 1)^2 = 4
The standard equation of a circle, with center in (a,b) and radius r, is: (x-a)2 + (y-b)2 = r2
x2 + (y - b)2 = b2 or, equivalently, x2 + y2 - 2by = 0
The line passing through the center of a circle with two endpoints on the circle is the circle's diameter.
Equation of circle: (x-3)^2 +(y+5)^2 = 13
It is (x + 2)^2 + (y + 3)^2 = 9
Perpendicular to a line passing through the center of the Earth.
A diameter.
Half of a sphere cut by a plane passing through its center.
diameter
A diameter is the length of a chord passing through the center of a circle.