Understanding the Graph of (x-1)^2 + (y+3)^2 = 4
The equation (x-1)^2 + (y+3)^2 = 4 represents a circle in the Cartesian coordinate system. Let's break down why and how to graph it.
The Standard Circle Equation
The standard form of a circle's equation is:
(x - h)^2 + (y - k)^2 = r^2
Where:
- (h, k) represents the center of the circle.
- r represents the radius of the circle.
Analyzing our Equation
Comparing our given equation (x-1)^2 + (y+3)^2 = 4 to the standard form, we can identify the following:
- Center: (h, k) = (1, -3)
- Radius: r^2 = 4, so r = 2
Graphing the Circle
-
Plot the Center: Locate the point (1, -3) on the coordinate plane. This will be the center of our circle.
-
Mark the Radius: From the center, move 2 units to the right, left, up, and down. These points will lie on the circle's circumference.
-
Connect the Points: Connect the points you marked in step 2 with a smooth curve to form the complete circle.
Key Points
- The equation (x-1)^2 + (y+3)^2 = 4 defines all the points that are exactly 2 units away from the point (1, -3). This is the very definition of a circle.
- The radius determines the size of the circle. A larger radius will result in a larger circle.
- The center determines the circle's position on the coordinate plane.
By understanding the standard circle equation and its components, you can easily graph any circle equation in the form (x - h)^2 + (y - k)^2 = r^2.