erplex
  • Lessons
  • Problems
  • Speed Run
  • Practice Tests
  • Skill Checklist
  • Review Videos
  • Landing Page
  • Sign Up
  • Login
  • erplex
    IB Math AASL
    /
    2D & 3D Geometry
    /

    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.

    2D & 3D Geometry

    Video Reviews

    Watch comprehensive video reviews for 2D & 3D Geometry, 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.

    Right TrianglesNon right trianglesCircles, arc, radians3D solids

    The video will automatically pause when it reaches a problem.

    Arc length

    SL 3.4

    Since the angle θ in radians is defined as the ratio of the arc length to the radius, the arc length is simply

    l=rθ📖

    as long as θ is in radians. If it is not, we first have to convert it to radians.


    Example

    A circle with radius 4cm has an arc with central angle 55°. Find the length of the arc.


    In radians, 55°=18055​⋅π=0.960. Therfore

    l=4⋅0.960=3.84cm

    Arc length

    SL 3.4

    Since the angle θ in radians is defined as the ratio of the arc length to the radius, the arc length is simply

    l=rθ📖

    as long as θ is in radians. If it is not, we first have to convert it to radians.


    Example

    A circle with radius 4cm has an arc with central angle 55°. Find the length of the arc.


    In radians, 55°=18055​⋅π=0.960. Therfore

    l=4⋅0.960=3.84cm
    Right TrianglesNon right trianglesCircles, arc, radians3D solids