Math Problem Statement

Graph y=3cot(3x+pi)-2

Solution

To graph the function y=3cot(3x+π)2y = 3\cot(3x + \pi) - 2, let's analyze its key properties.

Step 1: Identify Transformations

The parent function is y=cotxy = \cot x, which has:

  • Vertical asymptotes at x=kπx = k\pi (where kk is an integer).
  • Period of π\pi.
  • Zeroes at x=π2+kπx = \frac{\pi}{2} + k\pi.

Now, let's analyze the transformations:

  1. Horizontal Compression by a factor of 3

    • The period of y=cot(3x)y = \cot(3x) is given by:
      πB=π3\frac{\pi}{|B|} = \frac{\pi}{3}
    • This means that the cotangent function repeats every π3\frac{\pi}{3}.
  2. Phase Shift

    • The phase shift is determined by setting 3x+π=03x + \pi = 0, solving for xx: x=π3x = -\frac{\pi}{3}
    • This means the graph shifts left by π3\frac{\pi}{3}.
  3. Vertical Stretch by 3

    • The amplitude is scaled by 3, making the function steeper.
  4. Vertical Shift Down by 2

    • The entire graph moves down by 2 units.

Step 2: Locate Asymptotes

The vertical asymptotes occur where 3x+π=kπ3x + \pi = k\pi, solving for xx:

x=kππ3=kπ3π3x = \frac{k\pi - \pi}{3} = \frac{k\pi}{3} - \frac{\pi}{3}

Thus, asymptotes occur at:

x=kπ3π3,kZx = \frac{k\pi}{3} - \frac{\pi}{3}, \quad k \in \mathbb{Z}

Step 3: Plot Key Points

  1. Find where y=2y = -2 (midline).
  2. Find x-values where y=0y = 0 (cotangent zeroes).
  3. Sketch the asymptotes and the decreasing behavior of cotangent.

Graph Description

  • The function has vertical asymptotes at x=kπ3π3x = \frac{k\pi}{3} - \frac{\pi}{3}.
  • The period is π3\frac{\pi}{3}, meaning it repeats every π3\frac{\pi}{3}.
  • The graph is vertically stretched and shifted downward.
  • The cotangent function is decreasing between asymptotes.

Would you like me to generate an actual graph for you? Let me know if you have any questions!

Further Exploration Questions

  1. How would the graph change if we replaced cot\cot with tan\tan?
  2. What happens if we change the coefficient 3 in front of xx to another number?
  3. How does a vertical shift affect the asymptotes of a cotangent function?
  4. Can you find the x-intercepts of the transformed function?
  5. How would the period change if the equation was y=cot(5x)y = \cot(5x)?

Tip:

Remember that cotangent is undefined where sine is zero, so always check for vertical asymptotes first when graphing!

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Cotangent Function
Graph Transformations

Formulas

Period of cotangent: \frac{\pi}{|B|}
Phase Shift: \frac{-C}{B}
Asymptotes for cotangent: x = \frac{k\pi}{B} - \frac{C}{B} where k is an integer

Theorems

Graph transformations for trigonometric functions

Suitable Grade Level

Grades 10-12