Trigonometry Identities I Introduction

cos2x — cosx + 2 o Substitution (Double Angle Identity) Set equation equal to zero Re-arrange the polynomial F actor Solve 2cos x 2cos x 2cos x (2cosx 2cosx cosx 1 — cosx + 2 1 — cosx 2 cosx — 3 — 0 3)(cosx + 1) 0 1 cosx+ 1 0 cosx No Solution! (cost 1) COST' + 2 — ................
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