Every engineering discipline relies heavily on mathematics to describe and predict the behaviour of engineering systems.
Trigonometry is one of those fundamental mathematical concepts. From phasors in electrical engineering to force vectors in mechanical engineering, trigonometry comes is an essential part of the engineer’s toolset.
In this video, the Dennis Davis YouTube channel provides an excellent introduction to trigonometry concepts in a visual manner.
This would be a great introduction for undergraduate engineers or a good reference to refresh some concepts for professional engineers.