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Geometry

12 units · 64 topics · 2,076 lessons · Grade 9 or 10

Proof, transformations, congruence and similarity, right triangle trigonometry, circles, and area and volume.

Start: Points, Lines, and Planes Find a tutor Exam Sprint
  1. 1Tools of Geometry
  2. 2Reasoning and Proof
  3. 3Parallel and Perpendicular Lines
  4. 4Transformations
  5. 5Congruent Triangles
  6. 6Relationships Within Triangles
  7. 7Polygons and Quadrilaterals
  8. 8Similarity
  9. 9Right Triangles and Trigonometry
  10. 10Circles
  11. 11Area and Volume
  12. 12Probability
Course pathAll videos
1

Tools of Geometry

Points, lines, planes, and measuring segments and angles.

  1. 1Points, Lines, and PlanesUp next55 lessons
  2. 2Measuring Segments40 lessons
  3. 3The Midpoint and Distance Formulas42 lessons
  4. 4Measuring and Classifying Angles25 lessons
  5. 5Angle Pairs23 lessons
  6. 6Basic Constructions17 lessons
2

Reasoning and Proof

Conditional statements and writing proofs.

  1. 1Inductive and Deductive Reasoning42 lessons
  2. 2Conditional Statements39 lessons
  3. 3Algebraic Proof30 lessons
  4. 4Proving Segment and Angle Relationships44 lessons
3

Parallel and Perpendicular Lines

Transversals, angle relationships, and slopes.

  1. 1Parallel Lines and Transversals48 lessons
  2. 2Proving Lines Parallel20 lessons
  3. 3Perpendicular Lines and Distance31 lessons
  4. 4Slopes of Parallel and Perpendicular Lines19 lessons
4

Transformations

Rigid motions, dilations, and symmetry.

  1. 1Translations27 lessons
  2. 2Reflections24 lessons
  3. 3Rotations22 lessons
  4. 4Compositions of Transformations42 lessons
  5. 5Symmetry46 lessons
  6. 6Dilations33 lessons
5

Congruent Triangles

Triangle angle facts and proving triangles congruent.

  1. 1Triangle Angle Sum and Exterior Angles33 lessons
  2. 2Congruence and Rigid Motions71 lessons
  3. 3Proving Triangles Congruent: SSS and SAS34 lessons
  4. 4Proving Triangles Congruent: ASA, AAS, and HL20 lessons
  5. 5Using CPCTC37 lessons
  6. 6Isosceles and Equilateral Triangles38 lessons
6

Relationships Within Triangles

Midsegments, bisectors, centers, and triangle inequalities.

  1. 1Midsegments of Triangles34 lessons
  2. 2Perpendicular and Angle Bisectors49 lessons
  3. 3Points of Concurrency37 lessons
  4. 4Triangle Inequalities36 lessons
7

Polygons and Quadrilaterals

Polygon angles and the properties of special quadrilaterals.

  1. 1Angles of Polygons24 lessons
  2. 2Properties of Parallelograms23 lessons
  3. 3Proving a Quadrilateral Is a Parallelogram27 lessons
  4. 4Rectangles, Rhombuses, and Squares49 lessons
  5. 5Trapezoids and Kites46 lessons
  6. 6Coordinate Proofs35 lessons
8

Similarity

Similar figures and proportional reasoning.

  1. 1Similar Polygons45 lessons
  2. 2Proving Triangles Similar9 lessons
  3. 3Proportions in Triangles39 lessons
  4. 4Similar Right Triangles31 lessons
9

Right Triangles and Trigonometry

The Pythagorean theorem, special right triangles, and trig ratios.

  1. 1The Pythagorean Theorem and Its Converse46 lessons
  2. 2Special Right Triangles39 lessons
  3. 3Trigonometric Ratios25 lessons
  4. 4Solving Right Triangles13 lessons
  5. 5Angles of Elevation and Depression36 lessons
10

Circles

Arcs, angles, segments, and equations of circles.

  1. 1Parts of a Circle and Arcs5 lessons
  2. 2Arc Length and Radian Measure37 lessons
  3. 3Area of Sectors26 lessons
  4. 4Inscribed Angles38 lessons
  5. 5Tangent Lines14 lessons
  6. 6Chords, Secants, and Tangents45 lessons
  7. 7Equations of Circles30 lessons
11

Area and Volume

Measuring two- and three-dimensional figures.

  1. 1Areas of Polygons18 lessons
  2. 2Circumference and Area of Circles31 lessons
  3. 3Three-Dimensional Figures and Cross Sections41 lessons
  4. 4Surface Area45 lessons
  5. 5Volume of Prisms and Cylinders28 lessons
  6. 6Volume of Pyramids, Cones, and Spheres25 lessons
  7. 7Similar Solids and Modeling12 lessons
12

Probability

Counting outcomes and the rules of probability.

  1. 1Sample Spaces and Probability43 lessons
  2. 2Independent and Dependent Events38 lessons
  3. 3Conditional Probability26 lessons
  4. 4The Addition RuleCoverage growing
  5. 5Permutations and Combinations27 lessons