Free Christian Curriculum Kindergarten through twelfth grade · free to download

Grade 10 · 15 units · 160 lessons · 1,600 questions

Geometry

A full year of proof-based plane geometry, plus trigonometry, conics, and solid geometry, in 160 lessons.

About this course

This is a dedicated Geometry course, and proof is at the center of it. The year opens with points, lines, and planes, the ruler and protractor postulates, angle pairs, segment and angle bisectors, and the coordinate plane, then gives a full unit to logic and proof: inductive and deductive reasoning, conditional statements with their converse, inverse, and contrapositive, biconditionals, the laws of detachment and syllogism, the properties of equality used as reasons, and how to write a two-column, paragraph, or flow proof. From there come parallel lines and transversals, triangle congruence by SSS, SAS, ASA, and AAS, isosceles and equilateral triangles, the triangle inequality and midsegment theorems, similarity by AA, SAS, and SSS, the 45-45-90 and 30-60-90 special triangles, the Pythagorean theorem and its converse, quadrilaterals and polygon angle formulas, surface area and volume of prisms, pyramids, cones, and spheres, and a full unit on circles covering arcs, central and inscribed angles, sectors, chords, secants, and tangents.

The second half goes further than a standard geometry year. It covers transformations (reflections, rotations, translations, compositions, tessellations, and an introduction to fractals); right triangle trigonometry extended through inverse functions, the law of sines, the law of cosines, vectors and the dot product, and navigation by bearing; coordinate geometry with coordinate proofs, partitioning a segment, and locus; compass-and-straightedge construction, including the classical Greek problems and the golden ratio; analytic geometry with parabolas, ellipses, and hyperbolas identified by completing the square; geometric probability with Monte Carlo methods and expected value; three-dimensional geometry with polyhedra, Euler's formula, cross-sections, and nets; and a closing modeling unit that applies geometry to architecture, navigation, computer graphics, and conservation. The course is 160 lessons in 15 units of 10 to 12, at about 55 minutes each, which is a full year with a little slack in it since the daily-scheduled courses run 180. A lesson opens with prayer, states the definitions, postulates, or theorems for the day, works two to four examples with each step justified, adds an application and a short worldview note tied to a KJV verse, and ends with a ten-question multiple-choice quiz that grades itself. The writing is dense and compact, so the worked examples carry much of the teaching. Most units close with a review lesson, and the last unit reviews the whole year.

Materials are pencil, graph paper, a compass, a ruler, a protractor, and a Bible. The compass and protractor are genuinely used, since one full unit is straightedge-and-compass construction. Your student should finish Algebra I before starting. Geometry here leans on algebra constantly — solving equations for a missing side, slope and the equations of lines, the distance and midpoint formulas, simplifying radicals, and completing the square to identify a conic are all used without being retaught — and the trigonometry, vector, and conics units push past what a typical geometry course includes, so a student who is shaky on algebraic manipulation will struggle in the later units. Freedom Homeschool also offers a general Math course at tenth grade, and the two overlap. That course is chiefly advanced algebra and precalculus, with complex numbers, sequences and series, polynomial and rational functions, matrices, and logarithms, and geometry appears there as one strand among several. This course is the opposite balance: a full year of plane geometry with formal proof taught as a skill in its own right, which the general course touches but does not develop at this length. On a standard college-prep path Geometry usually comes after Algebra I and before advanced algebra, so for most families this is the tenth-grade math course rather than something added to it.

What the course covers

What your student will be able to do

Scope and sequence

All 15 units of Geometry for Grade 10, in the order they are taught.

Units in this course, in teaching order
UnitCoversLessonsQuestionsJump to lessons
Unit 1Foundations of Geometry12120Lessons
Unit 2Logic and Proof11110Lessons
Unit 3Parallel and Perpendicular Lines11110Lessons
Unit 4Triangle Similarity and Special Triangles11110Lessons
Unit 5Quadrilaterals and Polygons10100Lessons
Unit 6Circles11110Lessons
Unit 7Transformations10100Lessons
Unit 8Right Triangle Trigonometry12120Lessons
Unit 9Coordinate Geometry10100Lessons
Unit 10Geometric Constructions10100Lessons
Unit 11Analytic Geometry and Conics10100Lessons
Unit 12Geometric Probability10100Lessons
Unit 13Three-Dimensional Geometry10100Lessons
Unit 14Geometric Modeling and Applications11110Lessons
Unit 15Capstone Review11110Lessons

Every lesson, by title

All 160 lesson titles are listed here — nothing is withheld until you download. Open a unit to read its contents.

Unit 1: Foundations of Geometry 12 lessons
  1. 1Points, Lines, and Planes10 q
  2. 2Segments, Rays, and Angles10 q
  3. 3Measuring Segments — The Ruler Postulate10 q
  4. 4Measuring Angles — The Protractor Postulate10 q
  5. 5Angle Pairs — Complementary, Supplementary, and Vertical10 q
  6. 6Midpoints and Segment Bisectors10 q
  7. 7Angle Bisectors10 q
  8. 8Perimeter and Area of Basic Figures10 q
  9. 9The Coordinate Plane10 q
  10. 10The Distance Formula10 q
  11. 11The Midpoint Formula10 q
  12. 12Unit 1 Review — Foundations of Geometry10 q
Unit 2: Logic and Proof 11 lessons
  1. 1Inductive Reasoning and Conjectures10 q
  2. 2Conditional Statements — If-Then Form10 q
  3. 3Converse, Inverse, and Contrapositive10 q
  4. 4Biconditional Statements10 q
  5. 5Deductive Reasoning — Laws of Logic10 q
  6. 6Writing Two-Column Proofs10 q
  7. 7Properties of Equality Used in Proofs10 q
  8. 8Segment and Angle Addition Postulates in Proofs10 q
  9. 9Proving Angle Relationships — Vertical Angles Theorem10 q
  10. 10Paragraph and Flow Proofs10 q
  11. 11Unit 2 Review — Logic and Proof10 q
Unit 3: Parallel and Perpendicular Lines 11 lessons
  1. 1Lines and Angles Formed by Transversals10 q
  2. 2Proving Lines Parallel10 q
  3. 3Slopes of Parallel and Perpendicular Lines10 q
  4. 4Writing Equations of Parallel and Perpendicular Lines10 q
  5. 5Constructions — Parallel and Perpendicular Lines10 q
  6. 6Unit 3 Review — Parallel and Perpendicular Lines10 q
  7. 7Triangle Angle Sum and Exterior Angle Theorem10 q
  8. 8Triangle Congruence — SSS, SAS, ASA, AAS10 q
  9. 9Isosceles and Equilateral Triangles10 q
  10. 10Triangle Inequality and Midsegment Theorem10 q
  11. 11Unit 3–4 Review — Lines and Triangles10 q
Unit 4: Triangle Similarity and Special Triangles 11 lessons
  1. 1Introduction to Similar Figures10 q
  2. 2AA, SAS, and SSS Similarity Theorems10 q
  3. 3Triangle Proportionality Theorem10 q
  4. 4Special Right Triangles — 45-45-9010 q
  5. 5Special Right Triangles — 30-60-9010 q
  6. 6The Pythagorean Theorem and Its Converse10 q
  7. 7Trigonometric Ratios — Sine, Cosine, Tangent10 q
  8. 8Angles of Elevation and Depression10 q
  9. 9Perimeter and Area of Similar Figures10 q
  10. 10Dilations and Scale Drawings10 q
  11. 11Unit 4 Review — Similarity and Special Triangles10 q
Unit 5: Quadrilaterals and Polygons 10 lessons
  1. 1Properties of Parallelograms10 q
  2. 2Rectangles, Rhombuses, and Squares10 q
  3. 3Trapezoids and Kites10 q
  4. 4Angles in Polygons10 q
  5. 5Area of Quadrilaterals and Regular Polygons10 q
  6. 6Perimeter and Area on the Coordinate Plane10 q
  7. 7Surface Area of Prisms and Pyramids10 q
  8. 8Volume of Prisms and Cylinders10 q
  9. 9Volume of Pyramids, Cones, and Spheres10 q
  10. 10Unit 5 Review — Quadrilaterals and 3D Figures10 q
Unit 6: Circles 11 lessons
  1. 1Parts of a Circle10 q
  2. 2Arcs, Central Angles, and Inscribed Angles10 q
  3. 3Circumference and Arc Length10 q
  4. 4Area of Circles and Sectors10 q
  5. 5Equations of Circles10 q
  6. 6Chord and Tangent Relationships10 q
  7. 7Circumscribed and Inscribed Polygons10 q
  8. 8Angles Formed by Chords, Secants, and Tangents10 q
  9. 9Unit 6 Review — Circles10 q
  10. 10Geometric Probability — Length and Area10 q
  11. 11Unit 6 Capstone — Circles in Real Life10 q
Unit 7: Transformations 10 lessons
  1. 1Introduction to Transformations10 q
  2. 2Reflections10 q
  3. 3Rotations10 q
  4. 4Translations10 q
  5. 5Symmetry in God's Creation10 q
  6. 6Compositions and Congruence via Rigid Motions10 q
  7. 7Tessellations10 q
  8. 8Similarity Transformations and Fractals10 q
  9. 9Unit 7 Review — Transformations10 q
  10. 10Coordinate Geometry and Proofs10 q
Unit 8: Right Triangle Trigonometry 12 lessons
  1. 1SOH-CAH-TOA Review10 q
  2. 2Finding Missing Sides with Trig10 q
  3. 3Inverse Trig and Finding Angles10 q
  4. 4Angles of Elevation and Depression10 q
  5. 5Law of Sines10 q
  6. 6Law of Cosines10 q
  7. 7Applications: Surveying and Navigation10 q
  8. 8Vectors as Directed Segments10 q
  9. 9Dot Product and Angle Between Vectors10 q
  10. 10Navigation and Bearing Problems10 q
  11. 11Trig in Architecture and Construction10 q
  12. 12Unit 8 Review — Trigonometry10 q
Unit 9: Coordinate Geometry 10 lessons
  1. 1The Coordinate Plane Review10 q
  2. 2Distance Formula10 q
  3. 3Midpoint Formula10 q
  4. 4Slope and Lines10 q
  5. 5Coordinate Proofs10 q
  6. 6Partitioning a Line Segment10 q
  7. 7Circles in the Coordinate Plane10 q
  8. 8Locus and Geometric Places10 q
  9. 9Polygons on the Coordinate Plane10 q
  10. 10Unit 9 Review — Coordinate Geometry10 q
Unit 10: Geometric Constructions 10 lessons
  1. 1Tools of Construction10 q
  2. 2Copying Segments and Angles10 q
  3. 3Bisecting Segments and Angles10 q
  4. 4Constructing Perpendicular and Parallel Lines10 q
  5. 5Constructing Triangles and Regular Polygons10 q
  6. 6Constructions with Circles10 q
  7. 7Classical Geometry Problems10 q
  8. 8Constructions in Real Life10 q
  9. 9The Golden Ratio10 q
  10. 10Unit 10 Review — Constructions10 q
Unit 11: Analytic Geometry and Conics 10 lessons
  1. 1Introduction to Conic Sections10 q
  2. 2Parabolas10 q
  3. 3Ellipses10 q
  4. 4Hyperbolas10 q
  5. 5Identifying Conics from General Form10 q
  6. 6Completing the Square for Conics10 q
  7. 7Applications of Parabolas10 q
  8. 8Ellipses in Astronomy10 q
  9. 9Hyperbolas in Technology10 q
  10. 10Unit 11 Review — Conics10 q
Unit 12: Geometric Probability 10 lessons
  1. 1Introduction to Geometric Probability10 q
  2. 2Length and Segment Probability10 q
  3. 3Area Probability10 q
  4. 4Monte Carlo Methods10 q
  5. 5Probability and Circles10 q
  6. 6Expected Value and Geometry10 q
  7. 7Geometric Probability Applications10 q
  8. 8Volume Probability10 q
  9. 9Probability in Design and Nature10 q
  10. 10Unit 12 Review — Geometric Probability10 q
Unit 13: Three-Dimensional Geometry 10 lessons
  1. 1Points, Lines, and Planes in 3D10 q
  2. 2Polyhedra and Euler's Formula10 q
  3. 3Cross-Sections and Nets10 q
  4. 4Surface Area of Prisms and Pyramids10 q
  5. 5Volume of Prisms and Cylinders10 q
  6. 6Volume of Pyramids, Cones, and Spheres10 q
  7. 7The 3D Distance Formula and Midpoint10 q
  8. 8Density, Scale, and Modeling10 q
  9. 9Architecture and 3D Geometry10 q
  10. 10Unit 13 Review — 3D Geometry10 q
Unit 14: Geometric Modeling and Applications 11 lessons
  1. 1Modeling with Geometry10 q
  2. 2Scale Drawings and Maps10 q
  3. 3Similar Figures and Proportional Reasoning10 q
  4. 4Geometry in Nature10 q
  5. 5Geometry in Art and Architecture10 q
  6. 6Engineering and Design Applications10 q
  7. 7Trigonometry in Construction10 q
  8. 8Geometry and Navigation10 q
  9. 9Geometry in Computer Graphics10 q
  10. 10Stewardship: Geometry in Conservation10 q
  11. 11Unit 14 Review — Modeling and Applications10 q
Unit 15: Capstone Review 11 lessons
  1. 1Review: Foundations, Logic, and Proof10 q
  2. 2Review: Parallel Lines and Triangles10 q
  3. 3Review: Quadrilaterals and Polygons10 q
  4. 4Review: Circles10 q
  5. 5Review: Transformations and Congruence10 q
  6. 6Review: Trigonometry10 q
  7. 7Review: Coordinate Geometry and Conics10 q
  8. 8Review: Probability and 3D Geometry10 q
  9. 9Review: Constructions and Applications10 q
  10. 10Comprehensive Problem Solving10 q
  11. 11Final Exam Review and Course Celebration10 q

One whole lesson, exactly as it comes

This is a real lesson taken from the middle of the course — the teaching text, the practice, the homework, and the first three quiz questions with their answers. It is not a marketing excerpt.

Unit 8: Right Triangle Trigonometry · Lesson 5

Law of Sines

55 minutesPencilCompassRulerProtractorGraph paperBible (KJV)

What this lesson is for

  • Students will understand law of sines
  • Students will see God's geometric design in creation

The Law of Sines

The basic trig ratios (SOH-CAH-TOA) only work in right triangles. The Law of Sines extends trigonometry to any triangle — acute, right, or obtuse.

The Law of Sines

For any triangle with sides a, b, c opposite to angles A, B, C:

$$\frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C}$$

Or equivalently: $\frac{\sin A}{a} = \frac{\sin B}{b} = \frac{\sin C}{c}$

When to Use It

Use the Law of Sines when you know:

  • AAS — two angles and a non-included side
  • ASA — two angles and the included side
  • SSA — two sides and a non-included angle (the "ambiguous case")

Worked Example

Triangle ABC: A = 40°, B = 75°, a = 10. Find b. First: C = 180° − 40° − 75° = 65° Then: b/sin 75° = 10/sin 40° b = 10 sin 75°/sin 40° ≈ 10(0.966)/0.643 ≈ 15.0

The Ambiguous Case (SSA)

When given two sides and a non-included angle, there may be 0, 1, or 2 valid triangles. Always check: if the computed sine > 1, no triangle exists.

Christian Worldview

God's creation is not limited to perfect right angles. Rivers meander, mountains rise at oblique angles, fields are irregular polygons. The Law of Sines lets us measure God's creation in all its varied beauty.

Homework

Complete assigned practice problems. Show all work and label diagrams.

The first three of this lesson's 10 questions

The Law of Sines applies to:

  1. Right triangles only
  2. Acute triangles only
  3. Any triangle
  4. Equilateral triangles only
Show the answer

Answer: Any triangle

The Law of Sines states a/sin A =

  1. b/sin B
  2. b/cos B
  3. a/sin B
  4. sin B/b
Show the answer

Answer: b/sin B

In a triangle, if A = 50°, B = 70°, what is C?

  1. 50°
  2. 60°
  3. 70°
  4. 80°
Show the answer

Answer: 60°

Another 7 questions follow in the lesson itself, each one graded the moment it is answered.

What comes with the download

160 full lessons

Across 15 units, each with objectives, a teaching passage written to be read aloud, guided practice, and homework.

1,600 quiz questions

Graded the instant they are answered, each with the explanation of why that answer is right.

A gradebook that works

Every score kept, a running average maintained, and a breakdown unit by unit — all in the file itself, nothing sent anywhere.

Progress and attendance

Tick lessons off as they are finished, watch the completion bar fill, and mark days present, absent, or excused.

Report card and certificate

Both printable, with your student's name, the grades, and the dates already filled in.

Backup you control

Export every record to a file you keep, and read it back later. A lost browser cache cannot take the year with it.

An answer key

Hidden from the student by default, there for the parent marking the work.

Nothing that phones home

No ads, no affiliate links, no analytics, no fonts fetched from elsewhere. Unplug the network cable and every one of these files still works.

What you will need

Drawn from the materials named across all 160 lessons of this course. Most families already own most of it.

Download Geometry — Grade 10

Free, and free of everything else. 17 files, 15.6 MB in total. No account, no email address, no payment. What you download carries no advertising, no affiliate links and no tracking of any kind.