Chapter 2: Problem 27
Sketch the graph of the circle or semicircle. $$(x+3)^{2}+(y-2)^{2}=9$$
Short Answer
Expert verified
The graph is a circle centered at (-3, 2) with radius 3.
Step by step solution
01
Identify the Equation Type
The equation \((x+3)^{2}+(y-2)^{2}=9\) is in the standard form for a circle. The general form of a circle’s equation is \((x-h)^{2}+(y-k)^{2}=r^{2}\), where \((h, k)\) is the center and \(r\) is the radius.
02
Determine the Center
From the equation \((x+3)^{2}+(y-2)^{2}=9\), identify \(h = -3\) and \(k = 2\). So the center of the circle is at \((-3, 2)\).
03
Calculate the Radius
The equation \((x+3)^{2}+(y-2)^{2}=9\) shows that \(r^{2} = 9\). Taking the square root, we find the radius \(r = 3\).
04
Sketch the Circle
To sketch the circle, plot the center at \((-3, 2)\) on a coordinate plane. Then, use the radius \(r = 3\) to draw a circle by placing points 3 units away from the center in all directions. Connect these points to form the circle.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Equation of a Circle
The equation of a circle can be thought of as the blueprint for drawing a perfect round shape on a coordinate plane. It tells us everything we need about the circle: its position and size. In general, the equation of a circle is given in the format
- \( (x-h)^2 + (y-k)^2 = r^2 \)
- \((h, k)\): The center of the circle.
- \(r\): The radius of the circle.
Radius of a Circle
The radius is one of the most critical features of a circle. It's the constant distance from the center to any point on the edge of the circle. In the equation of a circle
- \((x-h)^2 + (y-k)^2 = r^2\)
Circle Graph Sketching
Sketching the graph of a circle involves a few reliable steps that make it easier. Let's break down the process:First, locate the center of the circle on your graph by finding the point \((h, k)\) from the equation. In our exercise, this point is \((-3, 2)\).Next, use the radius to draw the circle. For our example, the radius \(r\) is 3. Place a mark 3 units away from the center in all cardinal directions (up, down, left, right). Connect these marks with a smooth curve, making sure all parts of the circle are the same distance from the center. If done correctly, these steps will give a perfect circle on your graph!
Standard Form of a Circle
The standard form of a circle's equation is an incredibly helpful tool that simplifies understanding and working with circles. It appears as
- \((x-h)^2 + (y-k)^2 = r^2\)
- \(h\) and \(k\) are shifts from the origin, locating the circle's center.
- \(r^2\) represents the square of the radius of the circle.