These come from trigonometry. Trigonometry is a way to relate angles and lengths. Usually it is offered as a high school course, and it is also availible at community colleges and universities. The course should take about 1 semester, ~4 months.
This means "by how much the quantity changes." A good place to learn this math is in the first year of calculus, which you can only take after trigonometry. Another good place to learn about 'delta' is in an introductory physics course.
If you look at any curriculum for a computer science major at a US university, they usually have to take calculus and intro physics, which I think is a good idea.
After these classes you will be ready to learn about the Matrices that mgb_phys mentioned, but usually this course is taught after calculus, it's called Linear Algebra.