Sec 3: Circles*You will need graph paper

Homework: Pg 610 #12-22, 29, 31-36, 48

Learning Target: I will graph circles given an equation and write an equation given a graph.

Quality Core Review

x

y

Answer: B

The standard form of an equation of a circle with center (h, k) and radius r is

Standard Form of an Equation of a Circle

A. Center: (-4, 3) and radius = 4.

B. Center: (0, -2) and radius of 11.

Ex 1: Write the equation for the following circles.

C. D.

Ex 1 Continued

Graph (x – 16)² + (y + 9)² = 144

Center: Radius =

Domain: Range:

Ex 2: Graphing Circles Given an Equation

(16, -9)

√144 = 12

4 ≤ x ≤ 28

-21 ≤ y ≤ 3

A. (x + 8)² + (y + 3)² = 121

B. x² + y² = 10

Ex 3: State the Center, Radius, Domain and Range and then Graph the circle.

Center: (-8, -3) r = 11 D: -19 ≤ x ≤ 3 R: -14 ≤ y ≤ 8

Center: (0, 0) r = √10 or 3.2 D: -3.2 ≤ x ≤ 3.2 R: -3.2 ≤ y ≤ 3.2

Tell the Center and Radius for

Hint: Get rid of the coefficients that are causing the confusion!

Ex 4: This is Trickery!

A certain wi-fi phone has a range of 30 miles in any direction. If the phone is 4 miles south and 3 miles west of headquarters, write an equation to represent the area within which the phone can operate via the Wi-Fi system.

Ex 5: Wi-Fi

Pg 610 #12-22, 29, 31-36, 48

Homework