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Ch. R - Algebra Review
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161Not the one you use?Change textbook
Chapter 1, Problem 53

In the following exercises, (a) find the center-radius form of the equation of each circle described, and (b) graph it. See Examples 5 and 6.
center (2, 0), radius 6

Verified step by step guidance
1
Recall that the center-radius form of a circle's equation is given by \[(x - h)^2 + (y - k)^2 = r^2\] where \[(h, k)\] is the center and \[r\] is the radius.
Identify the center coordinates and radius from the problem: the center is \[(2, 0)\] and the radius is \[6\].
Substitute the center coordinates into the formula: replace \[h\] with \[2\] and \[k\] with \[0\], so the equation becomes \[(x - 2)^2 + (y - 0)^2 = r^2\].
Substitute the radius value into the equation: replace \[r\] with \[6\], so the equation becomes \[(x - 2)^2 + y^2 = 6^2\].
Simplify the right side by squaring the radius: the equation is \[(x - 2)^2 + y^2 = 36\]. This is the center-radius form of the circle's equation.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Equation of a Circle in Center-Radius Form

The center-radius form of a circle's equation is (x - h)² + (y - k)² = r², where (h, k) is the center and r is the radius. This form directly shows the circle's location and size, making it easy to write the equation when the center and radius are known.
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Coordinate Geometry and Plotting Points

Understanding how to plot points on the Cartesian plane is essential for graphing the circle. The center (h, k) is the reference point, and the radius determines the distance from the center to any point on the circle, guiding the drawing of the circle's boundary.
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Determining Different Coordinates for the Same Point Example 2

Radius and Distance in the Plane

The radius is the fixed distance from the center to any point on the circle. Knowing how to interpret and use this distance helps in both writing the equation and graphing the circle accurately, ensuring all points satisfy the distance condition.
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