Chapter 13: Problem 16
Find the center and radius of each circle and graph it. $$ x^{2}+y^{2}=16 $$
Short Answer
Expert verified
Center: (0, 0); Radius: 4
Step by step solution
01
Identify Circle Equation
The given equation is in the form of a circle: \( x^2 + y^2 = 16 \). This is a standard form of a circle equation centered at the origin when the equation is \( x^2 + y^2 = r^2 \).
02
Determine Center of the Circle
The standard circle equation \( (x - h)^2 + (y - k)^2 = r^2 \), tells us that the center of the circle \((h, k)\) is at the origin when no \(h\) or \(k\) terms are added/subtracted from \(x\) or \(y\). Thus, for \( x^2 + y^2 = 16 \), the center is at \((0, 0)\).
03
Calculate the Radius of the Circle
In the standard equation \( (x - h)^2 + (y - k)^2 = r^2 \), the term \(r^2\) corresponds to the number on the other side of the equation. Here, \(r^2 = 16\), so \(r = \sqrt{16} = 4\). Thus, the radius is 4.
04
Prepare to Graph the Circle
To graph the circle, begin by plotting the center at \((0, 0)\) on the coordinate plane. Use the radius of 4 to measure 4 units in all directions from the center, marking points on the circle's perimeter.
05
Draw the Circle
Using the center at \((0, 0)\) and radius of 4, draw a smooth, round circle that extends evenly 4 units up, down, left, and right from the center point.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Center of a Circle
The center of a circle is a crucial aspect of its geometry, serving as the fixed point equidistant from all points on the circle's edge. In the context of the standard form of a circle equation, which is \[(x - h)^2 + (y - k)^2 = r^2,\] the center is represented by the coordinates \((h, k)\).
- If both \(h\) and \(k\) are zero, meaning the equation simplifies to \[x^2 + y^2 = r^2,\] the center of the circle is located at the origin \((0, 0)\).
- Altering \(h\) and \(k\) shifts the circle on the coordinate plane away from the origin to the point \((h, k)\).
Radius of a Circle
The radius of a circle is the distance from the center of the circle to any point on its circumference. In the equation \[(x - h)^2 + (y - k)^2 = r^2,\] the term \(r^2\) signifies the square of the radius.
- To find the radius, simply take the square root of this number, \(r = \sqrt{r^2}\).
- This value is crucial, as it determines the size of the circle and is constant for any circle with a fixed equation.
Standard Form of a Circle Equation
The standard form of a circle equation is a valuable tool in geometry, as it defines the circle in a coordinate plane clearly and concisely. The typical form is written as \[(x - h)^2 + (y - k)^2 = r^2,\] where \((h, k)\) represents the circle's center and \(r\) the radius.
- This formulation provides an easy way to identify the circle's geometric properties, such as its center and radius, directly from the equation.
- It facilitates tasks like graphing and applying transformations such as translations and rotations.