Math Problem Statement

Graph y = 2 cot x and list the key points on the graph

Solution

To graph y=2cotxy = 2 \cot x, it's important to understand the properties of the cotangent function and how the coefficient affects its behavior.

Steps to Graph y=2cotxy = 2 \cot x:

  1. Basic Shape of cotx\cot x: The cotangent function, cotx=cosxsinx\cot x = \frac{\cos x}{\sin x}, has vertical asymptotes at points where sinx=0\sin x = 0, which occur at multiples of π\pi (i.e., x=0,π,2π,π,2πx = 0, \pi, 2\pi, -\pi, -2\pi, etc.).

    The cotangent function is undefined at these points, and the graph of cotx\cot x approaches these vertical asymptotes.

  2. Period: The period of cotx\cot x is π\pi, so the function repeats its behavior every π\pi units. This means that the graph of y=2cotxy = 2 \cot x will also repeat every π\pi.

  3. Amplitude: The coefficient 22 stretches the cotangent graph vertically by a factor of 2. This makes the graph steeper compared to y=cotxy = \cot x.

  4. Key Points: Let's list the key points for one period (from 00 to π\pi):

    • At x=π2x = \frac{\pi}{2}, the cotangent function crosses the x-axis. So, y(π2)=2×cot(π2)=0y( \frac{\pi}{2} ) = 2 \times \cot( \frac{\pi}{2} ) = 0.
    • As x0+x \to 0^+, cotx\cot x \to \infty, and since it's multiplied by 2, the value of yy \to \infty.
    • As xπx \to \pi^-, cotx\cot x \to -\infty, so yy \to -\infty.
  5. Graph Behavior:

    • The function decreases as xx moves from 0 to π\pi, starting from ++\infty, crossing the x-axis at x=π2x = \frac{\pi}{2}, and approaching -\infty as xπx \to \pi^-.

Summary of Key Points:

  • Vertical asymptotes: x=0,π,2π,π,2π,x = 0, \pi, 2\pi, -\pi, -2\pi, \dots
  • X-intercepts: x=π2,3π2,5π2,x = \frac{\pi}{2}, \frac{3\pi}{2}, \frac{5\pi}{2}, \dots
  • Behavior near asymptotes:
    • As x0+x \to 0^+, y+y \to +\infty
    • As xπx \to \pi^-, yy \to -\infty

Would you like me to graph this function for you?

Follow-up Questions:

  1. What is the effect of changing the coefficient in front of cotx\cot x?
  2. How does the period of cotx\cot x compare to that of sinx\sin x?
  3. What are the key points for y=cotxy = \cot x without the 2 as a multiplier?
  4. Can you explain the differences between tanx\tan x and cotx\cot x?
  5. How do vertical asymptotes influence the graph of trigonometric functions?

Tip:

Always remember that vertical asymptotes occur where the denominator of a fraction (like cotx=cosxsinx\cot x = \frac{\cos x}{\sin x}) is zero.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Cotangent Function
Graphing Trigonometric Functions

Formulas

y = 2 * cot(x)
cot(x) = cos(x) / sin(x)

Theorems

Periodicity of Trigonometric Functions
Properties of Cotangent Function

Suitable Grade Level

Grades 10-12