Get better at trig and so much more math at to get started for free for 30 days, and to get 20% off an annual premium subscription! This video is all about trigonometry, focusing on reviewing everything you are likely to actually use regularly in calculus. Instead of having to memorize a million trig identities I want to show how you can understand trig, where the formulas come from, and how you can figure them out on your own if you randomly need one in the middle of a test. ♡♡♡SUPPORT THE CHANNEL♡♡♡ ►Support on PATREON: ►MATH BOOKS I LOVE (affiliate link): ►CURIOSITY BOX: use CODE drtrefor for 25% off awesome STEM merch boxes 0:00 Trig Intro 0:40 Unit Circle Definitions 2:21 Why Radians 3:30 Pythagoras 4:02 Graphing cos and sin from unit circle 5:31 Special triangles 8:27 Computing Weird Trig Values 9:52 The other Trig Functions 10:49 Graphing Tan etc 13:31 Geometric Meaning of Sec and Tan 12:27 Other Pythagorean Identities 14:36 Trig Identities 16:27 Geometric Proof of Sum Rule 19:34 COURSE PLAYLISTS: ►DISCRETE MATH: ►LINEAR ALGEBRA: ►CALCULUS I: ►CALCULUS II: ►MULTIVARIABLE CALCULUS (Calc III): ►VECTOR CALCULUS (Calc IV) ►DIFFERENTIAL EQUATIONS: ►LAPLACE TRANSFORM: ►GAME THEORY: OTHER PLAYLISTS: ►Cool Math Series: ► Learning Math Series SOCIALS: ►X/Twitter: ►TikTok: @drtrefor ►Instagram (photography based):