Chapter 10: Problem 94
In Exercises 85-108, convert the polar equation to rectangular form. \(r=10\)
Short Answer
Expert verified
The rectangular form of the polar equation \(r=10\) is \(x^2 + y^2 = 100\).
Step by step solution
01
Understanding Polar Coordinates
Polar coordinates are represented as \(r,\theta\), where r represents the distance from the origin and \(\theta\) represents the angle measured in a counterclockwise direction from the positive x-axis. Any point in polar coordinates can be mapped into an equivalent point in Cartesian coordinates using the relationships \(x = rcos(\theta)\) and \(y = rsin(\theta)\).
02
Convert Polar to Rectangular
For the equation given, \(r=10\), we do not have an angle \(\theta\). However, we do know that regardless of what \(\theta\) is, the distance from the origin is always 10. This means that we are dealing with a circle centered at the origin with radius 10. The Cartesian equation for a circle centered at the origin is \(x^2 + y^2 = r^2\).
03
Substitution
Now we need to substitute \(r=10\) into the rectangular form equation from Step 2. When we substitute \(r=10\) into \(x^2 + y^2 = r^2\), we get \(x^2 + y^2 = 10^2\), which simplifies to \(x^2 + y^2 = 100\). This is the rectangular form of the polar equation \(r=10\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Polar Coordinates
Polar coordinates offer an alternative way to describe the location of a point in a plane. Imagine standing at the origin of a grid. Polar coordinates use two values to tell you how far and in what direction to move.
- The first value, \(r\), is the radial distance from the origin. Think of it as how many steps you take forward.
- The second value, \(\theta\), is the angle measured from the positive x-axis in a counterclockwise direction. It tells you which way to turn before you start walking.
Rectangular Coordinates
Rectangular coordinates, also known as Cartesian coordinates, use pairs \((x, y)\) to describe points on a plane. This method involves creating a grid with perpendicular axes. From the origin, you can:
- Move horizontally to find the \(x\)-coordinate.
- Move vertically to reach the \(y\)-coordinate.
Cartesian Equation of Circle
The Cartesian equation for a circle centered at the origin in rectangular coordinates is an elegant expression. A circle can be defined by its center and its radius, and for a circle at the origin, the equation is \[ x^2 + y^2 = r^2 \]where \(r\) is the radius of the circle.
- The equation represents all the points \((x, y)\) that are exactly \(r\) units away from the origin.
- It makes it easy to understand complex shapes by viewing the circle as an arrangement of points equidistant from a central point.