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Geometry Course
More than 2 million students worldwide

Geometry Course

Master every core concept in geometry — from foundational logic and proof writing to trigonometry, circles, and 3D measurement. This course builds the precise reasoning and problem-solving skills that power success in higher maths, engineering, and design. Whether you're strengthening your fundamentals or pushing toward advanced study, this is the geometry course that delivers results.

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What you will learn:

In this course, you will develop a complete understanding of geometry from the ground up. You will learn to write formal proofs, classify and analyse triangles and polygons, and apply the Theorem of Pythagoras and trigonometric ratios to real problems. You will explore parallel lines, circle theorems, coordinate geometry, and transformations on the coordinate plane. The course also covers area, surface area, and volume formulas for both two- and three-dimensional figures. By the end, you will have the skills to solve multi-step geometric problems with accuracy and confidence.

How you study in practice Geometry Course

How you practise Geometry Course

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Course content

8 Chapters • 37 LessonsDuration between 4 and 360 hours (you decide)

Chapter 1See details

Foundations of Geometric Thinking

  • Lesson 1 • Basic Geometric Constructions

    Covers compass-and-straightedge techniques for copying and bisecting segments and angles. Reinforces definitions through hands-on construction.

  • Lesson 2 • Distance and the Coordinate Plane

    Applies the distance formula and midpoint formula on the coordinate plane. Bridges abstract definitions to numerical computation.

  • Lesson 3 • Angles and Their Measurement

    Introduces angle types, degree measure, and the protractor postulate. Connects measurement skills to later work on triangles and polygons.

  • Lesson 4 • Points, Lines, and Planes

    Defines the three undefined terms that anchor all geometry. Establishes precise vocabulary used throughout every subsequent chapter.

Chapter 2See details

Reasoning, Proof, and Logic

  • Lesson 1 • Two-Column Proof Structure

    Teaches the statement-reason format for organising deductive arguments. Students practise writing complete proofs about segments and angles.

  • Lesson 2 • Inductive and Deductive Reasoning

    Contrasts pattern-based conjecture with logical deduction. Establishes the reasoning framework applied in every proof in the course.

  • Lesson 3 • Postulates and Theorems

    Distinguishes accepted postulates from proven theorems and explains how each functions in an argument. Builds the axiomatic foundation for all proofs.

  • Lesson 4 • Paragraph and Flow Proofs

    Introduces alternative proof formats that communicate reasoning in prose and diagrams. Strengthens flexibility in presenting geometric arguments.

Chapter 3See details

Parallel and Perpendicular Lines

  • Lesson 1 • Perpendicular Lines and Slopes

    Defines perpendicularity and connects it to slope relationships on the coordinate plane. Prepares students for coordinate geometry proofs.

  • Lesson 2 • Proving Lines Parallel

    Uses converse theorems to establish parallelism from angle evidence. Reinforces proof skills from Chapter 2 in a new context.

  • Lesson 3 • Properties of Parallel Lines

    Identifies corresponding, alternate interior, and co-interior angle pairs. Connects these relationships to the parallel postulate.

  • Lesson 4 • Angles Formed by Parallel Lines in Diagrams

    Applies angle-pair theorems to multi-step problems in complex figures. Develops fluency needed for triangle and polygon chapters.

Chapter 4See details

Triangles: Properties and Congruence

  • Lesson 1 • Congruence Postulates and Theorems

    Introduces SSS, SAS, ASA, AAS, and HL as tools for proving triangle congruence. Builds directly on proof skills from Chapter 2.

  • Lesson 2 • Triangle Classification and Angle Sums

    Classifies triangles by sides and angles and proves the triangle angle-sum theorem. Establishes properties referenced in every subsequent triangle topic.

  • Lesson 3 • Triangle Inequalities

    Establishes relationships between side lengths and angle measures within and between triangles. Prepares students for similarity and trigonometry.

  • Lesson 4 • CPCTC and Congruence Proofs

    Uses corresponding parts of congruent triangles to prove additional segment and angle relationships. Extends proof-writing to multi-step arguments.

  • Lesson 5 • Isosceles and Equilateral Triangles

    Proves and applies the isosceles triangle base-angles theorem and its converse. Connects special triangle properties to congruence criteria.

Chapter 5See details

Similarity and Proportional Reasoning

  • Lesson 1 • Indirect Measurement and Applications

    Applies similarity to measure inaccessible distances using shadow and mirror methods. Demonstrates real-world relevance of proportional reasoning.

  • Lesson 2 • Similar Polygons

    Defines similar polygons through congruent angles and proportional sides. Extends the concept beyond triangles to all polygon types.

  • Lesson 3 • Ratios, Proportions, and Scale

    Reviews ratio and proportion skills and introduces scale factor as a measure of similarity. Provides the algebraic tools needed for all similarity work.

  • Lesson 4 • Proportionality Theorems

    Covers the triangle proportionality theorem, its converse, and the midsegment theorem. Connects proportional reasoning to segment division.

  • Lesson 5 • Triangle Similarity Criteria

    Proves triangles similar using AA, SSS similarity, and SAS similarity. Builds on congruence criteria from Chapter 4 with a proportional extension.

Chapter 6See details

Right Triangles and Trigonometry

  • Lesson 1 • Angles of Elevation and Depression

    Applies trigonometric ratios to real-world height and distance problems. Develops problem-setup skills for applied geometry contexts.

  • Lesson 2 • The Theorem of Pythagoras

    Proves the Theorem of Pythagoras and its converse and classifies triangles by side lengths. Anchors all right-triangle computation in the chapter.

  • Lesson 3 • Special Right Triangles

    Derives exact side ratios for 45-45-90 and 30-60-90 triangles. Provides efficient shortcuts used in trigonometry and coordinate geometry.

  • Lesson 4 • Law of Sines and Law of Cosines

    Extends trigonometry to non-right triangles using the law of sines and cosines. Completes the toolkit for solving any triangle.

  • Lesson 5 • Trigonometric Ratios

    Defines sine, cosine, and tangent as ratios of sides in a right triangle. Connects ratio definitions to calculator-based computation.

Chapter 7See details

Polygons, Quadrilaterals, and Circles

  • Lesson 1 • Polygon Angle-Sum Theorems

    Derives interior and exterior angle-sum formulas for any convex polygon. Extends triangle angle reasoning to the general polygon case.

  • Lesson 2 • Inscribed and Circumscribed Polygons

    Explores polygons inscribed in and circumscribed about circles and their special properties. Connects circle theorems to polygon properties from earlier sections.

  • Lesson 3 • Circle Vocabulary and Arc Measures

    Introduces circle terminology and the relationship between central angles and arc measures. Establishes the vocabulary for all circle theorems.

  • Lesson 4 • Chord, Tangent, and Secant Theorems

    Proves theorems about chords, tangents, and secants and their angle and segment relationships. Builds a complete set of circle-line interaction rules.

  • Lesson 5 • Properties of Quadrilaterals

    Proves and applies properties of parallelograms, rectangles, rhombuses, squares, and trapeziums. Organises the quadrilateral hierarchy systematically.

Chapter 8See details

Area, Surface Area, and Volume

  • Lesson 1 • Surface Area of Solids

    Calculates lateral and total surface area of prisms, pyramids, cylinders, and cones using nets. Develops spatial reasoning for three-dimensional figures.

  • Lesson 2 • Circumference and Area of Circles

    Derives circumference and area formulas and applies them to sectors and segments. Connects circle measurement to arc and angle concepts from Chapter 7.

  • Lesson 3 • Similarity Ratios in Measurement

    Applies perimeter, area, and volume ratios of similar figures to solve scaling problems. Synthesises similarity from Chapter 5 with measurement from this chapter.

  • Lesson 4 • Volume of Solids

    Derives and applies volume formulas for prisms, pyramids, cylinders, cones, and spheres. Connects Cavalieri's principle to volume derivation.

  • Lesson 5 • Area of Polygons

    Derives area formulas for triangles, quadrilaterals, and regular polygons from first principles. Provides the two-dimensional foundation for surface area work.

Certification

Your valid completion certificate

This course is for you:

  • High school student: preparing for standardized tests and advanced math courses.

  • Architecture enthusiast: eager to understand the spatial logic behind structural design.

  • Career changer: entering construction, surveying, or engineering technology fields.

  • Adult learner: filling gaps from a geometry course taken years ago.

  • Visual artist or designer: wanting precise geometric tools for creative projects.

  • Pre-engineering student: building the mathematical foundation required for technical coursework.

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