In Exercises 71–76, eliminate the parameter and graph the plane curve represented by the parametric equations. Use arrows to show the orientation of each plane curve. x = 3 + 2 cos t, y = 1+2 sin t; 0 ≤ t < 2π
Table of contents
- 0. Review of College Algebra4h 45m
- 1. Measuring Angles40m
- 2. Trigonometric Functions on Right Triangles2h 5m
- 3. Unit Circle1h 19m
- 4. Graphing Trigonometric Functions1h 19m
- 5. Inverse Trigonometric Functions and Basic Trigonometric Equations1h 41m
- 6. Trigonometric Identities and More Equations2h 34m
- 7. Non-Right Triangles1h 38m
- 8. Vectors2h 25m
- 9. Polar Equations2h 5m
- 10. Parametric Equations1h 6m
- 11. Graphing Complex Numbers1h 7m
9. Polar Equations
Polar Coordinate System
Problem 81
Textbook Question
In Exercises 81–82, find the rectangular coordinates of each pair of points. Then find the distance, in simplified radical form, between the points. (2, 2π/3) and (4, π/6)
Verified step by step guidance1
Identify that the given points are in polar coordinates, where each point is given as \((r, \theta)\) with \(r\) being the radius (distance from the origin) and \(\theta\) the angle in radians.
Convert each polar coordinate to rectangular coordinates using the formulas: \(x = r \cdot \cos(\theta)\) and \(y = r \cdot \sin(\theta)\).
For the first point \((2, \frac{2\pi}{3})\), calculate \(x_1 = 2 \cdot \cos\left(\frac{2\pi}{3}\right)\) and \(y_1 = 2 \cdot \sin\left(\frac{2\pi}{3}\right)\).
For the second point \((4, \frac{\pi}{6})\), calculate \(x_2 = 4 \cdot \cos\left(\frac{\pi}{6}\right)\) and \(y_2 = 4 \cdot \sin\left(\frac{\pi}{6}\right)\).
Use the distance formula between two points in rectangular coordinates: \(d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}\), and simplify the expression to get the distance in simplified radical form.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Polar to Rectangular Coordinate Conversion
Polar coordinates (r, θ) represent points using a radius and an angle. To convert to rectangular coordinates (x, y), use x = r cos θ and y = r sin θ. This conversion is essential for comparing points or calculating distances in the Cartesian plane.
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Distance Formula in the Cartesian Plane
The distance between two points (x₁, y₁) and (x₂, y₂) in rectangular coordinates is given by the formula √[(x₂ - x₁)² + (y₂ - y₁)²]. This formula derives from the Pythagorean theorem and is used to find the straight-line distance between points.
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Quadratic Formula
Simplifying Radical Expressions
Simplifying radicals involves expressing square roots in their simplest form by factoring out perfect squares. This process makes the distance expression cleaner and easier to interpret, which is often required in final answers for trigonometry problems.
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