For me it’s been 20 years since college. I tried taking a trigonometry couse. Something I aced in college. Some parts were easy. But I kept running into refer

For me it’s been 20 years since college. I tried taking a trigonometry couse. Something I aced in college. Some parts were easy. But I kept running into references that I could not remember. Eventually I just had to back to pre-algebra. Most of it is trivial but I do keep finding things I had completely forgotten.