Hello students 👋 Please take time to go through these videos. They build on what you already know from trigonometry and basic differentiation, and they show how the trig derivatives come straight from first principles. 📘 Single-angle functions (sin x, cos x, tan x) 👉 https://youtu.be/hMmwgYiez-Q 📗 Multiple angles and half-angles (sin 2x, cos 2x, tan 2x) 👉 https://youtu.be/6fzq96E0sr0 🔍 These videos will help you: • Connect limits to the derivative rules • See how sin x turns into cos x • See why cos x becomes −sin x • Apply the same idea to 2x, 3x and other angle changes 💡 Reminder: trig functions starting with C give a negative sign. Watch, take short notes, and ask questions if anything is unclear.