Chapter 7: Problem 32
Convert the polar coordinates of each point to rectangular coordinates. $$\left(\sqrt{3}, 150^{\circ}\right)$$
Short Answer
Expert verified
The rectangular coordinates are \(-\frac{3}{2}, \frac{ \sqrt{3} }{ 2 } \).
Step by step solution
01
- Understand Polar Coordinates
The polar coordinates are given as \(( r, \theta )\), where \( r \) represents the radius and \( \theta \) represents the angle in degrees from the positive x-axis.
02
- Convert Angle to Radians
Since the conversion formulas use radians, convert \(150^{\circ} \) to radians using the formula \( \theta_{\text{radians}}= \theta_{\text{degrees}} \times \frac{ \pi }{ 180 } \). Hence, \(150^{\circ} = 150 \times \frac{ \pi }{ 180 } = \frac{ 5 \pi }{ 6 } \) radians.
03
- Use Conversion Formulas
Use the formulas \[ x = r \cos( \theta ) \]\ and \[ y = r \sin( \theta ). \]\
04
- Substitute Values
Substitute \( r = \sqrt{3} \) and \( \theta = \frac{ 5 \pi }{ 6 } \) into the formulas: \[ x = \sqrt{3} \cos( \frac{ 5 \pi }{ 6 }) \], \[ y = \sqrt{3} \sin( \frac{ 5 \pi }{ 6 }). \]\
05
- Calculate x-coordinate
Calculate \( x \) using \(\frac{ 5 \pi }{ 6 } \): \[ x = \sqrt{ 3 } \cos( \frac{ 5 \pi }{ 6 } ). \] The cosine of \( \frac{ 5 \pi }{ 6 } \) is \(-\frac{ \sqrt{ 3 } }{ 2 } \), so \[ x = \sqrt{ 3 } \times \left( -\frac{ \sqrt{ 3 } }{ 2 } \right) = -\frac{3}{2}. \]
06
- Calculate y-coordinate
Calculate \( y \) using \(\frac{ 5 \pi }{ 6 } \): \[ y = \sqrt{ 3 } \sin( \frac{ 5 \pi }{ 6 } ). \] The sine of \( \frac{ 5 \pi }{ 6 } \) is \frac{ 1 }{ 2 }, so \[ y = \sqrt{ 3 } \times \frac{ 1 }{ 2 } = \frac{ \sqrt{3 } }{ 2 }. \]
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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 system where each point on a plane is determined by a distance from a reference point and an angle from a reference direction. In this system, the coordinates are written as \( (r, \theta) \).
- \( r \) - This is the radius or the distance from the origin (which is the center point, usually considered as (0,0) in Cartesian coordinates).
- \( \theta \) - This is the angle measured from the positive x-axis to the line connecting the origin to the point in question.
Rectangular Coordinates
Rectangular coordinates (or Cartesian coordinates) describe a point in a plane using a pair of numbers (x, y). In this system, each point is defined by its horizontal distance from the y-axis and its vertical distance from the x-axis. Following this, we have:
\( x = r \cos(\theta) \)
\( y = r \sin(\theta) \).
- x-coordinate – The horizontal distance from the y-axis.
- y-coordinate – The vertical distance from the x-axis.
\( x = r \cos(\theta) \)
\( y = r \sin(\theta) \).
Angle Conversion
When working with trigonometric functions in mathematics, angles are most often required in radians rather than degrees. Radians provide a natural way of measuring angles based on the radius of a circle. To convert degrees to radians, we use the formula:
\( \theta_{\text{radians}} = \theta_{\text{degrees}} \times \frac{\pi}{180} \).
For example, converting \(150^{\circ}\) to radians: \(150^{\circ} \times \frac{ \pi }{ 180 } = \frac{ 5 \pi }{ 6 } \) radians.
This is crucial for using the trigonometric functions \( \cos(\theta) \) and \( \sin(\theta) \) correctly, as these functions require their input angle to be in radians.
\( \theta_{\text{radians}} = \theta_{\text{degrees}} \times \frac{\pi}{180} \).
For example, converting \(150^{\circ}\) to radians: \(150^{\circ} \times \frac{ \pi }{ 180 } = \frac{ 5 \pi }{ 6 } \) radians.
This is crucial for using the trigonometric functions \( \cos(\theta) \) and \( \sin(\theta) \) correctly, as these functions require their input angle to be in radians.