It depends. Between 9th to 12th.
It depends on what the school prefers. I would think that 9th graders in a school for kids with learning disabilities normally learn Pre-Algebra, or Algebra 1. For a 9th grade class in a mainstream school, I would think that most 9th graders would learn Algebra 1, Geometry, Algebra 2, or Trigonometry. I would think that Trigonometry is mostly for gifted 9th graders.
All math is related. In first grade you learn extremely simple math such as subtraction, addition, division and multiplication and in seventh grade you learn more complicated math, such as algebra or trigonometry. Math just gets more and more complicated the higher your grade level but it is still all related to math.
sin2A + cos2A
there is an introat the end of grade ten but there is a real unit in grade eleven trigonometry is usaully taken during geometry and parts of pre/calculus. Its about 10th and/or 11th grade!
In Geometry, you learn about triangles. In Trigonometry you learn even more about triangles.
Learn the subject!
The disadvantage of trigonometry is that it requires an intellectual effort to learn it. It is much easier to eat pizza, than it is to learn trigonometry. Put down that textbook and order a pizza. Yum!
Trigonometry isn't required to learn calculus, but it does help you to understand some of the concepts. Geometry, however, is usually required before taking a course in trigonometry.
SOH KAH TOA
If they put their mind to it, it is not difficult.
Im pretty sure he flunked it