Math Problem Statement

These are polar coordinates, find the ones that match with each other

These are polar coordinates, find the ones that match with each other.

Solution

To match polar coordinates that represent the same point, we need to understand the principles of polar coordinates. Polar coordinates are in the form (r,θ)(r, \theta), where rr is the radius (distance from the origin), and θ\theta is the angle. Two points represent the same location if either:

  1. The radius rr is the same, and the angle θ\theta is coterminal (differ by multiples of 2π2\pi).
  2. The radius rr is negated, and the angle θ\theta is shifted by π\pi (because negating the radius reverses the direction of the point).

Now let's analyze and match the given coordinates:

Given Coordinates:

  1. (3,5π4)(3, \frac{5\pi}{4})
  2. (3,3π4)(-3, \frac{3\pi}{4})
  3. (3,5π2)(-3, \frac{5\pi}{2})
  4. (3,3π2)(-3, \frac{3\pi}{2})

Coordinates to Match:

  1. (3,5π4)(3, \frac{5\pi}{4})
  2. (3,3π2)(-3, \frac{3\pi}{2})
  3. (3,3π4)(-3, \frac{3\pi}{4})
  4. (3,5π4)(3, \frac{5\pi}{4})

Solution:

Step-by-Step Matching:

  1. (3,5π4)(3, \frac{5\pi}{4}):

    • This has a positive radius r=3r = 3 and angle 5π4\frac{5\pi}{4}. To match, look for:
      • Same r=3r = 3, with a coterminal angle (5π4±2nπ\frac{5\pi}{4} \pm 2n\pi).
      • OR r=3r = -3, with θ=5π4+π\theta = \frac{5\pi}{4} + \pi (9π4\frac{9\pi}{4}).
    • Match: (3,5π4)(3, \frac{5\pi}{4}).
  2. (3,3π2)(-3, \frac{3\pi}{2}):

    • This has a negative radius r=3r = -3 and angle 3π2\frac{3\pi}{2}. To match, look for:
      • Opposite radius r=3r = 3 with θ=3π2+π=7π2\theta = \frac{3\pi}{2} + \pi = \frac{7\pi}{2} or coterminal.
    • Match: (3,3π2)(-3, \frac{3\pi}{2}).
  3. (3,3π4)(-3, \frac{3\pi}{4}):

    • This has a negative radius r=3r = -3 and angle 3π4\frac{3\pi}{4}. To match, look for:
      • Positive radius r=3r = 3, with θ=3π4+π=7π4\theta = \frac{3\pi}{4} + \pi = \frac{7\pi}{4} or coterminal.
    • Match: (3,3π4)(-3, \frac{3\pi}{4}).
  4. (3,5π2)(-3, \frac{5\pi}{2}):

    • This has a negative radius r=3r = -3 and angle 5π2\frac{5\pi}{2}. To match, look for:
      • Positive radius r=3r = 3, with θ=5π2+π=9π2\theta = \frac{5\pi}{2} + \pi = \frac{9\pi}{2} or coterminal.
    • Match: (3,5π2)(-3, \frac{5\pi}{2}).

Let me know if you need a more detailed breakdown! Here are some follow-up questions for you:

  1. What are coterminal angles in polar coordinates?
  2. How does the sign of the radius affect the angle in polar coordinates?
  3. How do we convert polar coordinates to rectangular coordinates?
  4. What are some practical applications of polar coordinates?
  5. How do θ\theta values beyond 2π2\pi impact matching points?

Tip: Remember that you can always add or subtract multiples of 2π2\pi to angles for coterminal points!

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Math Problem Analysis

Mathematical Concepts

Polar Coordinates
Coterminal Angles
Negative Radius Transformation

Formulas

Coterminal angles: θ + 2nπ (n ∈ Z)
Negative radius transformation: (r, θ) ↔ (-r, θ + π)

Theorems

Properties of polar coordinates

Suitable Grade Level

Grades 9-12