Chapter 10: Problem 53
A point in rectangular coordinates is given. Convert the point to polar coordinates. $$(-\sqrt{3},-\sqrt{3})$$
Short Answer
Expert verified
The polar coordinate of the point \(-\sqrt{3},-\sqrt{3}\) in rectangular coordinates is \(\sqrt{6}, \frac{5\pi}{4}\).
Step by step solution
01
Identify given coordinates
The point given is \(-\sqrt{3},-\sqrt{3}\) in rectangular coordinates. Let's call the x-coordinate as 'x' and the y-coordinate as 'y'. So, x = -\sqrt{3} and y = -\sqrt{3}.
02
Calculate the radial coordinate r
In polar coordinates, a point is described using a radial distance 'r' and an angle '\(\theta\)'. The radial coordinate 'r' is calculated as the square root of the sum of the squares of x and y. According to Pythagorean theorem, \(r= \sqrt{x^{2} + y^{2}}\). So, plugging the given x and y into the formula: \(r= \sqrt{(-\sqrt{3})^{2} + (-\sqrt{3})^{2}}\). This simplifies to \(r= \sqrt{6}\).
03
Find the angle \(\theta\)
Now, the angle '\(\theta\)' in polar coordinates can be found using the equation: \(\theta = \arctan\frac{y}{x}\) . But since the coordinates lie in the third quadrant (as both x and y are negative), we have to add PI to the result to get the correct angle. Plugging in the given y and x into the formula gives: \(\theta = \arctan\frac{-\sqrt{3}}{-\sqrt{3}}\). Solving this yields: \(\theta = \arctan(1) + \pi\). This simplifies to \(\theta = \frac{\pi}{4} + \pi = \frac{5\pi}{4}\).
04
Write down the polar coordinates
Finally, the polar coordinates are given as the radial distance 'r' and the angle '\(\theta\)'. Hence, the polar coordinate of the point \(-\sqrt{3},-\sqrt{3}\) is \(\sqrt{6}, \frac{5\pi}{4}\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Rectangular Coordinates
Rectangular coordinates, also known as Cartesian coordinates, describe a point in a two-dimensional plane using two numbers. These numbers represent distances along two perpendicular axes: the x-axis and the y-axis. For the point \(-\sqrt{3}, -\sqrt{3}\), the value of \(-\sqrt{3}\) for both coordinates shows its position relative to the origin (0,0). The x-coordinate \(-\sqrt{3}\) tells us how far the point is from the origin in the horizontal direction, while the y-coordinate \(-\sqrt{3}\) indicates its vertical distance from the origin.
Radial Distance
Radial distance, often denoted as \(r\) in polar coordinates, represents how far a point is from the origin, regardless of direction. This distance is always non-negative and can be calculated using the formula derived from the Pythagorean theorem: \[r = \sqrt{x^2 + y^2}\].
- In our example, for the coordinates \(-\sqrt{3}, -\sqrt{3}\), this formula becomes \[r = \sqrt{(-\sqrt{3})^2 + (-\sqrt{3})^2}\].
- This simplifies to \[r = \sqrt{6}\], indicating the point's radial distance from the origin.
Angle Conversion
In polar coordinates, the angle \(\theta\) describes the direction of the point relative to the positive x-axis. This angle is measured in radians.
- To find \(\theta\), use the arctangent function: \(\theta = \arctan\frac{y}{x}\).
- For the point \(-\sqrt{3}, -\sqrt{3}\), both \(x\) and \(y\) are negative, placing the point in the third quadrant where angles range from \(\pi\) to \(\frac{3\pi}{2}\).
Pythagorean Theorem
The Pythagorean theorem plays a vital role in converting rectangular coordinates to polar coordinates. This theorem states that in a right-angled triangle, the square of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides.
- When applying this to rectangular coordinates, the theorem helps calculate the radial distance \(r\) as \(r = \sqrt{x^2 + y^2}\).
- This formula comes directly from the idea that every point on the plane can form a right triangle with the origin, where \(x\) and \(y\) are the triangle's legs, and \(r\) is the hypotenuse.