Chapter 10: Problem 19
Express the following polar coordinates in Cartesian coordinates. \(\left(-4, \frac{3 \pi}{4}\right)\)
Short Answer
Expert verified
Answer: The Cartesian coordinates equivalent to the given polar coordinates are \((2\sqrt{2}, -2\sqrt{2})\).
Step by step solution
01
Identify the given polar coordinates
The given polar coordinates are \((-4, \frac{3\pi}{4})\). Here, \(r = -4\) and \(\theta = \frac{3\pi}{4}\).
02
Apply the conversion formulas
To convert the polar coordinates to Cartesian coordinates, we will use the following formulas:
\(x = r \cos(\theta)\)
\(y = r \sin(\theta)\)
03
Find the value of x
Using the conversion formula for \(x\), we have:
\(x = (-4) \cos\left(\frac{3\pi}{4}\right)\)
The cosine of \(\frac{3\pi}{4}\) is \(-\frac{\sqrt{2}}{2}\). So, we end up with:
\(x = (-4) \left(-\frac{\sqrt{2}}{2}\right) = 2\sqrt{2}\)
04
Find the value of y
Using the conversion formula for \(y\), we have:
\(y = (-4) \sin\left(\frac{3\pi}{4}\right)\)
The sine of \(\frac{3\pi}{4}\) is \(\frac{\sqrt{2}}{2}\). So, we end up with:
\(y = (-4) \left(\frac{\sqrt{2}}{2}\right) = -2\sqrt{2}\)
05
Write the final Cartesian coordinates
Now that we have the \(x\) and \(y\) values, we can write the Cartesian coordinates as \((x, y)\) or \((2\sqrt{2}, -2\sqrt{2})\). So, the Cartesian coordinates equivalent to the given polar coordinates are:
\((2\sqrt{2}, -2\sqrt{2})\)
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Polar Coordinates
Polar coordinates are a way to describe the position of a point in a plane using two values:
With the initial problem, the polar coordinates given are \((-4, \frac{3\pi}{4})\). This means:
- the distance from the origin (often represented as \(r\))
- the angle from the positive x-axis (represented by \(\theta\))
With the initial problem, the polar coordinates given are \((-4, \frac{3\pi}{4})\). This means:
- The point is 4 units away from the origin, but moving in the opposite direction since \(r\) is negative
- The direction or angle is \(\frac{3\pi}{4}\) radians from the positive x-axis
Cartesian Coordinates
Cartesian coordinates are used to define a point in space through two coordinate axes intersecting at the origin:
- The x-coordinate tells how far along the horizontal axis the point is
- The y-coordinate informs how far along the vertical axis the point exists
- An x-value of \(2\sqrt{2}\), indicating the point’s distance to the right of the origin
- A y-value of \(-2\sqrt{2}\), showing that the point is downward from the origin
Coordinate Transformation
Coordinate transformation involves converting between different measures of describing a point's location, such as from polar to Cartesian coordinates. To accomplish this:
This conversion process is critical in fields requiring precise physical placement, motion analysis, or solving complex equations where a coordinate transformation can simplify the task.
- The formulas \(x = r \cos(\theta)\) and \(y = r \sin(\theta)\) are vital
- \(x = (-4) \cos(\frac{3\pi}{4}) = 2\sqrt{2}\)
- \(y = (-4) \sin(\frac{3\pi}{4}) = -2\sqrt{2}\)
This conversion process is critical in fields requiring precise physical placement, motion analysis, or solving complex equations where a coordinate transformation can simplify the task.