# Lesson 3Circle ChallengesPractice Understanding

Find the perimeter of each polygon.

## Set

### 5.

Write the equation of circle .

### 6.

The point is the center of a circle with a radius of . Does the point lie inside, outside, or on the circle? Explain your answer.

### 7.

The diameter of a circle measures units and the center is at the intersection of and . Prove that the equation of the circle is .

### 8.

Triangle is inscribed in . Segment passes through the center of and to the -axis. All vertices of lie on the circle. Use the information in the diagram to write the equation of . Justify that your equation is correct.

### 9.

A circle lies in Quadrant II, tangent to and and the -axis. Find the center and radius of the circle. Then write the equation of the circle.

### 10.

Three points on a circle are , , and . Draw a diagram to explain why the equation of the circle is .

### 11.

Complete the square to find the center and radius of a circle defined by the equation .

### 12.

Complete the square to find the center and radius of a circle defined by the equation .

## Go

Fill in the number that completes the square. Then write the trinomial as the square of a binomial.

Factored form:

Factored form:

Factored form:

Factored form:

Factored form:

Factored form:

Factored form:

Factored form: