Exercise 6 Page 733

Practice makes perfect

(x- a)^2+(y- b)^2= r^2 [-1em] Midpoint:& ( a, b) Radius:& r

From our diagram we can identify the midpoint and radius.

Let's substitute this information in the general formula. (x- 0)^2+(y- 0)^2= 3^2 [-1em] Midpoint:& ( 0, 0) Radius:& 3 This simplifies to x^2+y^2=9.

b If we compare the given equation to the general equation of a circle, we notice that it has a midpoint of (0,0) and a radius of 7, since 7^2=49.

(x- 0)^2+(y- 0)^2= 7^2 [-1em] Midpoint:& ( 0, 0) Radius:& 7 Now we can sketch the graph.

12.1.1 The Equation of a Circle p.733-734

12.1.2 Completing the Square for Equations of Circles p.738-741

12.1.3 Introduction to Conic Sections p.744-745

12.1.4 Graphing a Parabola Using The Focus and Directrix p.749-750

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