Math Problem Statement

Convert the polar coordinates left parenthesis, 2, square root of, 3, end square root, comma, start fraction, 7, pi, divided by, 6, end fraction, right parenthesis(2 3 ​ , 6 7π ​ ) into rectangular form. Express your answer in simplest radical form.

Solution

The polar coordinates (23,7π6)(2\sqrt{3}, \frac{7\pi}{6}) can be converted to rectangular coordinates (x,y)(x, y) using the following formulas:

x=rcosθx = r \cos \theta y=rsinθy = r \sin \theta

where r=23r = 2\sqrt{3} and θ=7π6\theta = \frac{7\pi}{6}.

Step 1: Calculate xx

x=23cos(7π6)x = 2\sqrt{3} \cdot \cos\left(\frac{7\pi}{6}\right) The angle 7π6\frac{7\pi}{6} is in the third quadrant, where cosine is negative. The reference angle is π6\frac{\pi}{6}, and cos(π6)=32\cos\left(\frac{\pi}{6}\right) = \frac{\sqrt{3}}{2}. Therefore: cos(7π6)=32\cos\left(\frac{7\pi}{6}\right) = -\frac{\sqrt{3}}{2} Now substitute: x=23(32)=3x = 2\sqrt{3} \cdot \left(-\frac{\sqrt{3}}{2}\right) = -3

Step 2: Calculate yy

y=23sin(7π6)y = 2\sqrt{3} \cdot \sin\left(\frac{7\pi}{6}\right) In the third quadrant, sine is also negative. The reference angle is π6\frac{\pi}{6}, and sin(π6)=12\sin\left(\frac{\pi}{6}\right) = \frac{1}{2}. Therefore: sin(7π6)=12\sin\left(\frac{7\pi}{6}\right) = -\frac{1}{2} Now substitute: y=23(12)=3y = 2\sqrt{3} \cdot \left(-\frac{1}{2}\right) = -\sqrt{3}

Final Answer:

The rectangular coordinates are (3,3)(-3, -\sqrt{3}).

Do you need further details or explanations? Here are five related questions you could explore:

  1. How are reference angles used when converting polar coordinates?
  2. What are the signs of trigonometric functions in each quadrant?
  3. How can you convert rectangular coordinates back to polar coordinates?
  4. What are the unit circle values for common angles like π6\frac{\pi}{6}?
  5. How do trigonometric functions change as the angle increases?

Tip: Always check which quadrant an angle lies in to determine the correct sign of sine and cosine.

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Math Problem Analysis

Mathematical Concepts

Polar Coordinates
Rectangular Coordinates
Trigonometric Functions

Formulas

x = r * cos(θ)
y = r * sin(θ)

Theorems

Trigonometric Function Signs in Quadrants
Reference Angle Calculation

Suitable Grade Level

Grades 10-12