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Memorizing Trigonometric Identities with Hexagon

Aug 24, 2024

Super Hexagon and Trigonometric Identities

Overview

  • The super hexagon is a geometric figure that helps in memorizing trigonometric formulas and identities.
  • It consists of a hexagon with diagonals and specific functions written at the vertices.

Structure of the Super Hexagon

  • Hexagon Setup:

    • Draw a hexagon and join opposite vertices to create three diagonals.
    • Place the number 1 in the center.
  • Vertices and Functions:

    • Begin at a vertex and write the functions in clockwise order:
      • tan, sine, cosine
    • The opposite vertex of tan is cot.
    • Remaining functions:
      • cosec opposite to sec (all c's on the right).

Basic Trigonometric Relationships

  • Starting from tan:
    • tan θ = sine θ / cos θ
    • sine θ = cos θ / cot θ
    • cos θ = cot θ / cosec θ
    • cot θ = cosec θ / sec θ
    • cosec θ = sec θ / tan θ
    • sec θ = tan θ / sine θ

Anti-clockwise Direction

  • Relationships still hold when moving anti-clockwise:
    • tan θ = sec θ / cosec θ
    • sine θ = tan θ / sec θ
    • cos θ = sine θ / tan θ

Reciprocal Relationships

  • Functions at diagonally opposite vertices are reciprocals:
    • sine θ = 1/cosec θ
    • cos θ = 1/sec θ
    • cot θ = 1/tan θ

Complementary Angles

  • Special relationship with complementary angles (sum equals 90 degrees):
    • sine θ = cos(90° - θ)
    • tan θ = cot(90° - θ)
    • sec θ = cosec(90° - θ)
    • cos θ = sin(90° - θ)

Pythagorean Identities

  • Form triangles within the hexagon:

  • Important identities derived:

    • sine² θ + cos² θ = 1
    • 1 + cot² θ = cosec² θ
    • tan² θ + 1 = sec² θ
  • Anti-clockwise relations lead to:

    • 1 - cos² θ = sine² θ
    • cosec² θ - cot² θ = 1
    • sec² θ - 1 = tan² θ

Conclusion

  • The super hexagon serves as a powerful tool for remembering numerous trigonometric formulas.
  • It is vital to practice the positions, directions, and relationships of the functions.
  • The video serves as a supplementary resource, emphasizing the importance of understanding the derived formulas rather than just memorizing them.