Question

Which equations represent circles that have a diameter of 12 units and a center that lies on the y-axis? Select two options.

x2 + (y – 3)2 = 36
x2 + (y – 5)2 = 6
(x – 4)² + y² = 36
(x + 6)² + y² = 144
x2 + (y + 8)2 = 36

Answer 1

Since the center of the circle lies on the y-axis, the x-coordinate of the center must be 0.

Also, since the diameter of the circle is 12 units, the radius is half of that, or 6 units.

Using the standard form of the equation of a circle, which is (x - h)^2 + (y - k)^2 = r^2, where (h, k) is the center of the circle and r is the radius, we can substitute the values we know and simplify the equations to see which ones match.

The equations that represent circles with a diameter of 12 units and a center that lies on the y-axis are:

x^2 + (y - 6)^2 = 36 (center is at (0, 6))

x^2 + (y + 6)^2 = 36 (center is at (0, -6))

Therefore, the two options that represent the circles with the given properties are:

x^2 + (y - 6)^2 = 36 and x^2 + (y + 6)^2 = 36.