In 9th grade (I think), I sat through a whole year of trig - and got absolutely NOTHING out of it. I tried to read the book - NOTHING clicked. The instructor - was, for me, a complete dud.
Many years later, one of the engineers at a place I worked at spent about 20 minutes explaining the basic idea (with a circle and triangles) and then the basic idea clicked. A few years later another student (at the community college) explained SAH-COH-TOA - and another light bulb went on. Can I use trig well? No - but at least I have an idea of how it works.
I use my calculator to pull up the angles for the Triangle in a Square units.(Peaky and Spike as Doreen Speckmann called the unit.)
I continue to have those AHA!!!! moments - when I could use a concept - but then when I UNDERSTOOD the concept! - that is such a joy when that happens.