erplex
  • Lessons
  • Problems
  • Speed Run
  • Practice Tests
  • Skill Checklist
  • Review Videos
  • Landing Page
  • Sign Up
  • Login
  • erplex
    IB Math AASL
    /
    Trig equations & identities
    /

    Video

    Video Reviews

    Watch comprehensive video reviews for most units, designed for final exam preparation. Each video includes integrated problems you can solve alongside detailed solutions.

    Not your average video:

    Interactive Problems: Solve problems alongside the video with step-by-step guidance and detailed solutions.

    Exam Preparation: Complete unit reviews designed for final exam preparation with all key concepts covered systematically.

    Expert Teaching: High-quality instruction from Perplex co-founder James Mullen with clear explanations, worked examples, and exam tips.

    Not your average video:

    Interactive Problems: Solve problems alongside the video with step-by-step guidance and detailed solutions.

    Exam Preparation: Complete unit reviews designed for final exam preparation with all key concepts covered systematically.

    Expert Teaching: High-quality instruction from Perplex co-founder James Mullen with clear explanations, worked examples, and exam tips.

    Trig equations & identities

    Video Reviews

    Watch comprehensive video reviews for Trig equations & identities, designed for final exam preparation. Each video includes integrated problems you can solve alongside detailed solutions.

    Not your average video:

    Interactive Problems: Solve problems alongside the video with step-by-step guidance and detailed solutions.

    Exam Preparation: Complete unit reviews designed for final exam preparation with all key concepts covered systematically.

    Expert Teaching: High-quality instruction from Perplex co-founder James Mullen with clear explanations, worked examples, and exam tips.

    Not your average video:

    Interactive Problems: Solve problems alongside the video with step-by-step guidance and detailed solutions.

    Exam Preparation: Complete unit reviews designed for final exam preparation with all key concepts covered systematically.

    Expert Teaching: High-quality instruction from Perplex co-founder James Mullen with clear explanations, worked examples, and exam tips.

    Unit circleTrig functionsTrig equationsIdentitiesHL functionsHL Identities

    The video will automatically pause when it reaches a problem.

    Cosine double angle identity

    SL 3.6

    The double angle identity for cosine states that

    cos2θ  ​=cos2θ−sin2θ=2cos2θ−1=1−2sin2θ​📖


    Example

    Given that sinθ=53​ and cosθ=−54​, find cos2θ.

    cos2θ=(−54​)2−(53​)2=257​

    Cosine double angle identity

    SL 3.6

    The double angle identity for cosine states that

    cos2θ  ​=cos2θ−sin2θ=2cos2θ−1=1−2sin2θ​📖


    Example

    Given that sinθ=53​ and cosθ=−54​, find cos2θ.

    cos2θ=(−54​)2−(53​)2=257​
    Unit circleTrig functionsTrig equationsIdentitiesHL functionsHL Identities