The video below (9:51 min) is the first in the comprehensive Essence of linear algebra YouTube playlist (16 videos) from 3Blue1Brown.
This video (36:21 min) makes an attempt to teach the fundamentals of calculus 1 such as limits, derivatives, and integration.
This video (41:07 min) provides a basic introduction to trigonometry including how to evaluate trigonometric functions (sin, cos, tan) using SOH CAH TOA and right triangle trigonometry, and how to use reference angles and coterminal angles.
