# Lesson 6Turn It AroundPractice Understanding

## Ready

Use the distance formula to find . Leave in radical form.

## Set

The focus, , and the equation of the directrix are given. The coordinates for points and are also given. Make a sketch of the given information. Then use the diagram and the distance formula to prove that points and lie on the same parabola.

• focus:

• directrix:

• : :

• focus:

• directrix:

• : :

• focus:

• directrix:

• : :

• focus:

• directrix:

• : :

## Go

Use the given information to write the equation of the circle.

### 8.

Center: , Radius:

### 9.

Endpoints of the diameter: and

### 10.

Center: Point on the circle:

### 11.

Equation of the circle in the diagram: