### 1.8 – Coordinate Geometry

## Video 1 of 3: Coordinate Plane and Geometry

## Video 2 of 3: Graphing Circles

## Video 3 of 3: Tangent Line to a Circle

# Section Notes

### Distance Formula

The distance between the points and is given by

### Midpoint Formula

The midpoint of the line segment between points and is

### Intercepts

**x-intercepts** are the coordinates of points where the graph of an equation intersects the axis. To find them, set and solve for .

**y-intercepts** are the coordinates of points where the graph of an equation intersects the axis. To find them, set and solve for .

### Equation of a Circle

The equation of a circle with center and radius is

This is the **standard form** for the equation of a circle. A circle with radius and center at the origin has the equation

### Symmetry

**Symmetry with respect to the** **axis** occurs when the equation is unchanged when is replaced with

**Symmetry with respect to the ****axis** occurs when the equation is unchanged when is replaced with

**Symmetry with respect to the origin** occurs when the equation is unchanged when and are replaced by and , respectively.