Math Problem Statement

Which polar coordinates can represent the rectangular coordinates given below (-4√3, -4)?

Solution

To solve this question, we need to convert the given rectangular coordinates (43,4)(-4\sqrt{3}, -4) into polar coordinates.

Steps to convert rectangular coordinates to polar coordinates:

  1. Find the radius rr: The radius rr is given by: r=x2+y2r = \sqrt{x^2 + y^2} Here, x=43x = -4\sqrt{3} and y=4y = -4, so: r=(43)2+(4)2=48+16=64=8r = \sqrt{(-4\sqrt{3})^2 + (-4)^2} = \sqrt{48 + 16} = \sqrt{64} = 8

  2. Find the angle θ\theta: The angle θ\theta is given by: θ=tan1(yx)\theta = \tan^{-1}\left(\frac{y}{x}\right) Substituting x=43x = -4\sqrt{3} and y=4y = -4: θ=tan1(443)=tan1(13)\theta = \tan^{-1}\left(\frac{-4}{-4\sqrt{3}}\right) = \tan^{-1}\left(\frac{1}{\sqrt{3}}\right) From trigonometry, tan1(13)=π6\tan^{-1}\left(\frac{1}{\sqrt{3}}\right) = \frac{\pi}{6}. Since both xx and yy are negative, the point is in the third quadrant, so: θ=π+π6=7π6\theta = \pi + \frac{\pi}{6} = \frac{7\pi}{6}

  3. Write the polar coordinates: The polar coordinates are (r,θ)=(8,7π6)(r, \theta) = (8, \frac{7\pi}{6}). Alternatively, if rr is negative, the angle shifts by π\pi. So (r,θπ)(-r, \theta - \pi) is equivalent: (8,π6)(-8, \frac{\pi}{6})

Matching with the options:

The correct polar coordinates corresponding to (43,4)(-4\sqrt{3}, -4) are (8,π6)(-8, \frac{\pi}{6}), which is Option C.


Let me know if you'd like any part of this calculation clarified!

Follow-up Questions:

  1. How are polar and rectangular coordinate systems related geometrically?
  2. Why does the angle shift by π\pi when the radius is negative?
  3. Can a point have multiple polar coordinate representations?
  4. How can you verify polar coordinates by converting them back to rectangular form?
  5. What is the significance of quadrants in determining the angle?

Tip:

Always ensure that the angle θ\theta matches the quadrant of the rectangular coordinates when converting!

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Math Problem Analysis

Mathematical Concepts

Polar Coordinates
Rectangular Coordinates
Trigonometry

Formulas

r = √(x² + y²)
θ = tan⁻¹(y / x)
θ (quadrant adjustment)

Theorems

Trigonometric relationships for angle computation
Conversion between coordinate systems

Suitable Grade Level

Grades 10-12