Understanding the Equation (x-1)^2 + (y+3)^2 = 9
The equation (x-1)^2 + (y+3)^2 = 9 represents a circle in the Cartesian coordinate system. Let's break down why and explore its key features.
The Standard Form of a Circle
The general equation of a circle 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 (x-1)^2 + (y+3)^2 = 9
Comparing our given equation to the standard form, we can identify:
- Center (h, k): (1, -3)
- Radius r: 3
This means our circle is centered at the point (1, -3) and has a radius of 3 units.
Visualizing the Circle
To visualize the circle, we can follow these steps:
- Plot the center: Locate the point (1, -3) on the coordinate plane.
- Mark the radius: From the center, move 3 units to the right, left, up, and down. These points will lie on the circle's circumference.
- Connect the points: Draw a smooth curve connecting the points you marked. This curve represents the circle.
Key Points
- The equation defines a set of all points that are exactly 3 units away from the point (1, -3).
- Every point on the circle satisfies the equation (x-1)^2 + (y+3)^2 = 9.
- The equation can be used to find the coordinates of points on the circle, and vice versa.
Applications
Circles are fundamental geometric shapes with applications in various fields, including:
- Geometry: Calculating area, circumference, and other properties.
- Physics: Describing the motion of objects in circular paths.
- Engineering: Designing circular structures, gears, and other components.
- Computer Graphics: Creating and manipulating circular objects.
Understanding the equation (x-1)^2 + (y+3)^2 = 9 provides a foundation for exploring the properties and applications of circles in various contexts.