Syllabus and and other important documents

Syllabus

This syllabus contains important information about the course, including its goals, assignments, policies, resources, and expectations.

How to make custom tools on GeoGebra Classic?

A tutorial to create custom tools on GeoGebra Classic.

Euclid's Elements

Week 1 Lecture 1: A first look at Euclid’s

A first introduction to Euclid’s geometry, the axiomatic method, primitive terms, postulates, models, and Euclid’s first propositions.

Week 1 Lecture 2: Euclid’s rigor, constructions, and angles

A discussion of the six parts of a proposition, Euclid’s rigor in Propositions I.1, I.2, and I.4, constructions in GeoGebra Classic, angle definitions. Click on activity W1L2 for the GeoGebra constructions we did in class.

Homework 1

Homework 1 for MATH 128A.

Week 2 Lecture 1: “summary diagrams”, “Euclid-style” proofs, and more on postulates

A discussion of proposition “summary diagrams”, “Euclid-style” proofs, stronger forms of Postulates 1 and 2, and the definition of right angles and Postulate 4.

Week 2 Section Worksheet

A worksheet on Euclid-style proofs, summary diagrams, and constructions from Book I.

Week 2 Lecture 2: ASA, parallel lines, and angle sums in triangles

A discussion of the ASA and AAS congruence theorems, parallel lines and Postulate 5, basic properties of parallel lines, the construction of a parallel line through a point, and the angle sum in a triangle.

Homework 2

Homework 2 for MATH 128A.

Week 3 Lecture 1: Angles in triangles, RASS, and the center of a circle

A discussion of the sum of the angles in a triangle, polygons and convexity, the RASS congruence theorem, an application to chords in a circle, and the construction of the center of a circle.

Week 3 Section Worksheet

A worksheet on constructions, the RASS theorem, and inscribed/circumscribed circle to a triangle.

Week 3 Lecture 2: Tangents and angles in circles

A discussion of tangent lines, tangent circles, the relation between tangency and perpendicularity to the radius, and the main angle theorems in circles.

Homework 3

Homework 3 for MATH 128A.

Homework 3 Solutions

Solutions to Homework 3 for MATH 128A.

Hilbert's Axioms

Week 4 Lecture 1: Hilbert’s axioms, models, and parallel properties

An introduction to Hilbert’s axiomatic approach to Euclidean geometry, the axioms of incidence, models of incidence geometry, the Euclidean/elliptic/hyperbolic parallel properties, and isomorphisms of models.

Week 4 Section Worksheet

A worksheet on incidence geometry and parallel properties.

Week 4 Lecture 2

Affine planes.

Homework 4 Solutions

Solutions to Homework 4 for MATH 128A.

Week 5 Lecture 1

Affine planes and the number of points on lines.

Mock Midterm Exam

A worksheet to help you prepare for the midterm.

Homework 5

Homework 5 for MATH 128A.

Homework 5 Solutions

Solutions to Homework 5 for MATH 128A.

Week 6 Lecture 1

Counting points in affine planes, projective planes, and the first idea of projective completion.

Week 6 Section Worksheet: Counting in Affine and Projective Planes

In this worksheet, we study several counting arguments in affine and projective planes. We first prove that any two lines in a projective plane have the same number of points. We then deduce the standard formula for the number of points in a finite projective plane. Finally, we prove that in a finite affine plane of order \(n\), every point lies on exactly \(n+1\) lines.

Week 6 Lecture 2

Projective completion, points at infinity, and models of the real projective plane.

Homework 6

Homework 6 for MATH 128A.

Week 7 Lecture 1: Visualizing Projective Completions

Visualizing the real projective plane and introducing homogeneous coordinates.

Week 7 Section Worksheet: Homogeneous Coordinates and Projective Completion

The purpose of this worksheet is to make sure you have a solid understanding of homogeneous coordinates and to fill in some of the gaps from Section 11 of W7L1.

Week 7 Lecture 2 and Week 8 Lecture 1

Transformations of incidence geometries, permutations, examples, and the group structure of automorphisms.

Homework 7

Homework 7 for MATH 128A.

Homework 7 Solutions

Solutions to Homework 7.

Week 8 Lecture 2

Groups of transformations, with a detailed activity on the transformations of the integer line.

Homework 8

Homework 8 for MATH 128A.

Homework 8 Solutions

Solutions to Homework 8 for MATH 128A.

Week 9 Lecture 1

Finishing the transformations of the integer line, then introducing Pappus’ theorem and the reduction from the affine plane to the projective plane.

Week 9 Section Worksheet: Transformations of Infinite Incidence Geometries

The purpose of this worksheet is to classify all transformations of two infinite incidence geometries.

Week 9 Lecture 2

Continuing Pappus’ theorem: reducing the affine statement to the projective statement, introducing projective transformations, and normalizing the two lines.

Homework 9

Homework 9 for MATH 128A.

Week 10 Lecture 1

Finishing the proof of Pappus’ theorem in the normalized case, then concluding the course by discussing Hilbert planes and Euclidean planes.

Week 10 Section Worksheet: Transformations, Ceva, and Conics

This worksheet explores how transformations can simplify geometric proofs. We prove Ceva’s theorem by affine normalization and prove that five points determine a conic by projective normalization.

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