Math Problem Statement

suppose a point has polar coordinates (-3,5pi/6) find two additonal polar representatioons of the point

Solution

The given polar coordinates are (3,5π6)(-3, \frac{5\pi}{6}). In polar coordinates, we have the radius rr and the angle θ\theta, and the point can be represented in multiple ways.

To find two additional representations:

  1. Adjust the angle by 2π2\pi (adding or subtracting full rotations):

    • The polar coordinates are periodic with a period of 2π2\pi, so we can add or subtract multiples of 2π2\pi to θ\theta to find equivalent points.

    • If we add 2π2\pi to 5π6\frac{5\pi}{6}, we get:

      θ=5π6+2π=5π6+12π6=17π6\theta = \frac{5\pi}{6} + 2\pi = \frac{5\pi}{6} + \frac{12\pi}{6} = \frac{17\pi}{6}

      So, one representation is:

      (3,17π6)\left(-3, \frac{17\pi}{6}\right)

  2. Change the sign of rr and adjust θ\theta by π\pi:

    • If we negate rr, we reverse the direction of the point, but we need to adjust the angle by adding π\pi to account for the change in direction. This will give another valid representation.

    • If we change r=3r = -3 to r=3r = 3, then we add π\pi to the angle 5π6\frac{5\pi}{6}:

      θ=5π6+π=5π6+6π6=11π6\theta = \frac{5\pi}{6} + \pi = \frac{5\pi}{6} + \frac{6\pi}{6} = \frac{11\pi}{6}

      So, another representation is:

      (3,11π6)(3, \frac{11\pi}{6})

Final Answer:

  • (3,17π6)(-3, \frac{17\pi}{6})
  • (3,11π6)(3, \frac{11\pi}{6})

Let me know if you'd like more clarification!

Related Questions:

  1. How do you convert between rectangular and polar coordinates?
  2. How does changing the angle affect the location of a point in polar coordinates?
  3. What are the general rules for finding equivalent polar coordinates?
  4. What is the significance of negative rr in polar coordinates?
  5. How do you handle angles outside the typical range of [0,2π)[0, 2\pi)?

Tip: When working with polar coordinates, always remember that adding 2π2\pi or subtracting it from the angle θ\theta results in an equivalent point, but you must consider the sign of rr when adjusting the angle!

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Math Problem Analysis

Mathematical Concepts

Polar Coordinates
Trigonometry
Coordinate Geometry

Formulas

Polar coordinates conversion
Periodic nature of polar coordinates

Theorems

Properties of polar coordinates (periodicity and sign inversion)

Suitable Grade Level

Grades 9-12