Final answer:
To write the equation of a circle, use the formula (x - h)^2 + (y - k)^2 = r^2. Substituting the given values of center and radius, we can find the equations of the circles.
Step-by-step explanation:
The equation of a circle in a Cartesian coordinate system is (x - h)² + (y - k)² = r², where (h, k) is the center of the circle and r is the radius.
Here are the circle equations for the provided centers and radius/diameter values:
- Center: (-3, 4), Radius: 7
The equation is (x + 3)² + (y - 4)² = 49.
- Center: (-9, 0), Diameter: 20, Radius: 10
The equation is (x + 9)² + y² = 100.
- Center: (-7, -1), Diameter: 9, Radius: 4.5
The equation is (x + 7)² + (y + 1)² = 20.25.
- Center: (12, 5), Radius: √89
The equation is (x - 12)² + (y - 5)² = 89.