Chapter 1: Problem 129
In the following exercises, plot the point whose polar coordinates are given by first constructing the angle \(\theta\) and then marking off the distance \(r\) along the ray. $$\left(1, \frac{\pi}{4}\right)$$
Short Answer
Expert verified
Plot the point 1 unit from the origin at a 45-degree angle to the x-axis.
Step by step solution
01
Understand Polar Coordinates
Polar coordinates are given as a pair \(r, \theta\), where \(r\) is the distance from the origin and \(\theta\) is the angle from the positive x-axis. The given coordinates are \(\left(1, \frac{\pi}{4}\right)\), meaning the point is 1 unit from the origin and forms an angle of \(\frac{\pi}{4}\) (or 45 degrees) with the positive x-axis.
02
Construct the Angle \(\theta\)
Start from the positive x-axis, which can be considered as the direction of zero degrees or zero radians. Rotate counterclockwise to form the angle \(\frac{\pi}{4}\), equivalent to 45 degrees. Visualize or use a protractor to find this angle on your coordinate plane.
03
Mark the Distance \(r\)
From the origin (0,0), move along the line that makes a 45-degree angle from the positive x-axis. Measure and mark a point that is 1 unit away from the origin along this direction. This distance \(r = 1\) is straightforward and can usually be marked with a compass or a ruler.
04
Plot the Point
The point is now established by the intersection of the distance \(r=1\) along the angle \(\theta = \frac{\pi}{4}\). Ensure the point is placed accurately at 1 unit from the origin along the line making a 45-degree angle.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Angle Theta
In polar coordinates, angle \( \theta \) is a fundamental element that helps us determine the direction of a point from the origin.To visualize this, picture the coordinate plane with the central point known as the origin, and imagine a line or ray extending to the right as the positive x-axis.This position represents \(0\) degrees or \(0\) radians. To find angle \( \theta \), start from this positive x-axis and rotate counterclockwise.In our example, \( \theta = \frac{\pi}{4} \), which corresponds to a 45-degree rotation.
- Counterclockwise movement is considered positive.
- \( \theta \) defines the angle between the positive x-axis and the line connecting the origin to the point.
- For angles larger than \(2\pi\), continue rotating past \(360\) degrees accordingly.
Distance R
Distance \( r \) in polar coordinates indicates how far the point is from the origin.It's similar to the concept of radius in a circle.For the coordinates \((1, \frac{\pi}{4})\), the distance \( r = 1 \) tells us that the point lies exactly one unit away from the origin, in the direction specified by \( \theta \).
- \( r \) is always non-negative; a negative \( r \) often means moving in the opposite direction of \( \theta \).
- A larger \( r \) means the point is farther from the origin; the plot becomes larger in the same angle direction.
- Use a compass or a ruler for accuracy when plotting distance \( r \).
Coordinate Plane
The coordinate plane is a two-dimensional space where points are plotted based on two reference axes: the x and the y.In polar coordinates, however, we rely on \( r \) and \( \theta \) to plot points instead of traditional x and y coordinates.
- The origin is the central point, denoted by (0,0) in Cartesian coordinates.
- For polar plotting, the positive x-axis is your starting reference line.
- Think of each point as sitting on a ray originating from the origin, defined by \( \theta \) and extending for distance \( r \).
Plotting Points
Plotting a point in polar coordinates involves combining both the angle \( \theta \) and the distance \( r \).Visualize it as drawing a line from the origin, rotating it to the correct angle, and then marking off the distance.
- Start by finding \( \theta \) – rotate your line counterclockwise from the positive x-axis.
- Next, mark the distance \( r \) from the origin to locate exactly where the point lies on this ray.
- Check stability and precision; ensure no overlap with other plotted points.