Chapter 11: Problem 38
Convert the point from rectangular coordinates into polar coordinates with \(r \geq 0\) and \(0 \leq \theta<2 \pi\) \((3, \sqrt{3})\)
Short Answer
Expert verified
The polar coordinates are \((2\sqrt{3}, \frac{\pi}{6})\).
Step by step solution
01
Determine the Radius
To find the radius \( r \), we use the formula for converting rectangular coordinates to polar coordinates: \( r = \sqrt{x^2 + y^2} \). This gives us:\[ r = \sqrt{3^2 + (\5\u202664;3)^2} = \sqrt{9 + 3} = \sqrt{12} = 2\sqrt{3} \].Thus, the radius is \( r = 2\sqrt{3} \).
02
Determine the Angle
Next, we calculate the angle \( \theta \) using the formula \( \theta = \arctan\left(\frac{y}{x}\right) \). Substituting the given values, we have:\[ \theta = \arctan\left(\frac{\sqrt{3}}{3}\right) \].Since \( \tan(\frac{\pi}{6}) = \frac{\sqrt{3}}{3} \), it follows that \( \theta = \frac{\pi}{6} \). As both \( x \) and \( y \) are positive, the point is in the first quadrant, and thus the angle is still \( \frac{\pi}{6} \).
03
Verify the Quadrant
Verify that the calculated angle \( \theta \) falls in the correct quadrant. Since the point \((3, \sqrt{3})\) lies in the first quadrant where both \( x \) and \( y \) are positive, the angle \( \theta = \frac{\pi}{6} \) is valid for this quadrant.
04
Write the Polar Coordinates
Finally, we can express the point \((3, \sqrt{3})\) in polar coordinates as \((r, \theta)\). From our calculations, we know \( r = 2\sqrt{3} \) and \( \theta = \frac{\pi}{6} \). Thus, the polar coordinates are:\[ (2\sqrt{3}, \frac{\pi}{6}) \].
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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 a different way of looking at locations on a plane. Instead of using horizontal and vertical axes as in rectangular (or Cartesian) coordinates, polar coordinates use a distance and an angle. The distance is from a fixed reference point, typically called the origin, and the angle is measured from the positive x-axis.
- Distance is denoted by \( r \), which represents how far the point is from the origin. It is always non-negative (\( r \geq 0 \)) to ensure a valid location in space.
- Angle is represented as \( \theta \), which describes the rotation needed from the positive x-axis to the line connecting the origin to the point. Angles are measured in radians, with a complete circle being \( 2\pi \).
Rectangular Coordinates
Rectangular coordinates are probably the most familiar way to locate a point on a plane. This system uses two perpendicular axes - typically called the x-axis and the y-axis - to describe the position of a point.
- X-coordinate tells you how far left or right the point is from the origin.
- Y-coordinate describes how far up or down the point is from the origin.
Trigonometric Functions
Trigonometric functions play a crucial role in converting between rectangular and polar coordinates. They relate the angles and sides of triangles, which is essential in this conversion.For polar conversion, the primary functions used are:
- Sine (\( \sin \)) and Cosine (\( \cos \)): Used in polar coordinates to express the vertical and horizontal component of a radius.
- Tangent (\( \tan \)): Specifically useful for determining the angle \( \theta \) when converting from rectangular to polar coordinates using \( \theta = \arctan\left(\frac{y}{x}\right) \).
Quadrants in Coordinate Plane
The coordinate plane is divided into four quadrants, each one representing a unique combination of positive and negative x and y values. This division is crucial when determining the correct angle \( \theta \) in polar coordinates.
- First Quadrant: Both \( x \) and \( y \) are positive, \((+,+)\).
- Second Quadrant: \( x \) is negative and \( y \) is positive, \((- ,+)\).
- Third Quadrant: Both \( x \) and \( y \) are negative, \((-,-)\).
- Fourth Quadrant: \( x \) is positive and \( y \) is negative, \((+, -)\).