Identidades Trigonométricas | Introducción

Picked one by one from a mixed channel. Transcript check: both title readers certain; 3 of 5 sampled certain picks confirmed by transcript, none failed. Channel rule:

A 12-minute video from Matemáticas profe Alex: “Trigonometric Identities | Introduction”.

Video by Matemáticas profe Alex, played through YouTube's embedded player.