← All 9 coursesPC / Advanced
Precalculus
Orbit Observatory

Connect functions, trigonometry, complex numbers, vectors and linear transformations.
Preparation: Intermediate algebra, coordinate geometry, radicals and function notation.
Current coverage: 12 core stages covering domains, trigonometric identities, polar coordinates and 2D/3D vector methods.
4Topic levels
12Knowledge stages
528Practice problems
1LEVEL 1 · DIFFICULTY 1/5 within this course
Functions and Circular Measurement
Connect domains, radians and coordinates.
Explore 3 knowledge islands
3 stages · 24 library problems · 108 checked variations · 2 × 6 assessment questions
Read the lessons →2LEVEL 2 · DIFFICULTY 2/5 within this course
Trigonometric Relationships
Combine rotations and solve nonright triangles.
Explore 3 knowledge islands
3 stages · 24 library problems · 108 checked variations · 2 × 6 assessment questions
Read the lessons →3LEVEL 3 · DIFFICULTY 3/5 within this course
Polar, Complex and Vector Coordinates
Use coordinate systems suited to the problem.
Explore 3 knowledge islands
3 stages · 24 library problems · 108 checked variations · 2 × 6 assessment questions
Read the lessons →4LEVEL 4 · DIFFICULTY 4/5 within this course
Matrices and Space
Measure orientation and describe planes.
Explore 3 knowledge islands
3 stages · 24 library problems · 108 checked variations · 2 × 6 assessment questions
Read the lessons → Progress earned through practice
Clear a stage by independently solving two different routine problems and one application in a new context. Hints help you learn; hinted answers and repeated solves do not count toward that target. Clear every stage to clear a level.
Every stage includes an explanation, two worked examples and eight library practice problems, plus checked variations with changing numbers and applications. Each level also has a separate unit test and a later review form. Parents see actual attempts, hint use and results.
These are independently authored core-skills courses, with the current scope listed for each course. They do not reproduce complete textbook contents. Difficulty describes the teaching sequence within each course; course preparation matters when comparing subjects. This site is not affiliated with or endorsed by AoPS. Results reflect these exercises and are not standardized scores. Content release math-courses-2026.09.08-v4.