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Graphing Trigonometric Functions

Jun 21, 2024

Graphing Trigonometric Functions: A Complete Guide

Overview

  • Covers graphing sine, cosine, tangent, secant, cosecant, and cotangent functions.
  • Introduction to transformations: shifting, stretching, compressing.
  • Reference to the unit circle for graph origins.

Basic Sine Graph

  • Equation: y = sin(x)
  • Key Points:
    • 0 radians: sin value = 0
    • Ï€/2 or 90 degrees: sin value = 1
    • Ï€ or 180 degrees: sin value = 0
    • 3Ï€/2 or 270 degrees: sin value = -1
    • 2Ï€ or 360 degrees: sin value = 0
  • Shape: Repeats starting at the midline, maxima at 1, minima at -1.
  • Amplitude (2sin(x)):
    • Vertical stretch of 2: maxima at 2, minima at -2.
  • Period (sin(2x)):
    • Period = 2Ï€/B
    • Calculation: B = 2 → Period = Ï€
    • Graph divided into 4 parts.
  • Transformation (sin(x + Ï€) - 2):
    • Right shift by Ï€, down shift by 2.

Basic Cosine Graph

  • Equation: y = cos(x)
  • Key Points:
    • 0 radians: cos value = 1
    • Ï€/2 or 90 degrees: cos value = 0
    • Ï€ or 180 degrees: cos value = -1
    • 3Ï€/2 or 270 degrees: cos value = 0
    • 2Ï€ or 360 degrees: cos value = 1
  • Shape: Starts at maximum, goes to midline, minimum, then repeats.
  • Reflections and Periods:
    • Negative reflection flips graph over x-axis.
    • Half B value changes period (cos(1/2x)): Period = 4Ï€.
  • Transformation (cos(x - Ï€/2) + 1):
    • Right shift by Ï€/2, up shift by 1.

Advanced Examples

  • Multiple transformations (3sin(1/2x - Ï€) - 2):
    • Period = 4Ï€, right shift by Ï€, down shift by 2, amplitude stretch to 3.
  • Secant and Cosecant Graphs:
    • Based on cosine and sine graphs respectively.
    • Vertical asymptotes at x-intercepts of parent function.
    • Reflections and stretches applied as described.

Tangent Graph

  • Basics:
    • Tangent is y/x from the unit circle.
    • Period = Ï€/B
    • Key points and asymptotes from -Ï€/2 to Ï€/2.
  • Transformations:
    • Coefficient affects vertical stretch/shrink.
    • Period = Ï€/1/2 = 2Ï€
    • Examples with phase shift and vertical shift.

Cotangent Graph

  • Basics:
    • Cotangent is x/y from the unit circle.
    • Period = Ï€/B
    • Key points and asymptotes from 0 to Ï€.
  • Transformations:
    • Reflections, phases, and vertical shifts discussed.

Conclusion

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