Geometric Series Lecture Notes

Jul 17, 2024

Continue with Geometric Series

  • Importance: Common in mocks, prone to errors.
    • Stats: Only 10-12% get these questions right in mocks.

Key Concept: Triangle Inequality Theorem

  • Theorem Statement: For any triangle, the sum of any two sides must be greater than the third side.
    • Example: If sides are labeled p, q, and r, then:
      • p + q > r
      • p + r > q
      • q + r > p

Problem-Solving Strategy

  1. Given Condition: Sum of two sides is greater than the third side.
  2. Equation: p² + q² >= 2pq
  3. Transfer to form: (p - q)² >= 0
    • Always true because a perfect square is non-negative.
  4. New Formulation:
    • Add and manipulate sides, example:
      • p² + q² greater than another term.
    • When transforming, ensure addition aligns with the inequality:
      • (p + q)² >= 2pq
  5. Insight: p² + q² is always positive.
  6. Finding Correct Answer:
    • Simplify to fit into solution space.
    • Example simplification: p² + q² >= r²

Common Pitfalls

  • Missteps: Incorrectly introducing negative signs can lead to confusion.
  • Tip: Always ensure transformations preserve positive squares.

Application and Solution

  1. Inequalities and Relationships:
    • p² + q² >= 2pq is greater than 0
    • Leads to solutions fitting the criteria outlined.
  2. Final Solution:
    • Identify correct transformation to arrive at the right answer.
    • Example: p² + q²/r² >= 1/2 leads to solution.
      • Answer: 1/2

Practical Use

  • Triangular Relations: Commonly used in various geometric problems.
  • Reminder: Implement these methods to approach complex mocks and real-world geometric scenarios effectively.