Trigonometric Identities — 2 Proofs + Bonus Double Angle Identity

Learn how to prove two key trigonometric identities — both derived directly from the Pythagorean identity sin²θ + cos²θ = 1. Plus a bonus derivation of the alternate forms of cos(2θ). 📐 1 + cot²θ = cosec²θ 1 + tan²θ = sec²θ ⏱️ Timestamps: 0:00 – The two identities we're proving 0:20 – Starting point: sin²θ + cos²θ = 1 1:30 – Proof 1: 1 + cot²θ = cosec²θ (divide by sin²θ) 4:00 – Proof 2: 1 + tan²θ = sec²θ (divide by cos²θ) 5:20 – Bonus: deriving the alternate forms of cos(2θ) Yusuf holds a master's degree in mathematics from the University of Cape Town (UCT), with more than 15 years of experience teaching mathematics to primary, high school, and university students. This channel is set up with the aim of making maths make sense — fun, simple, and educational, with tricks, methods, and interesting concepts. Please subscribe, like, share, and follow me on this journey. Let's build a community of maths gurus! #TrigIdentities #Trigonometry #MathsProof #LearnMaths #MathsWithYusuf