Derivatives of Sine and Cosine Functions

Derivative of cos(x Next, we isolate the term 2 cos(x) cos(x 2 sin(x) cos(x) + 2 cos(x) cos(x) as follows: cos cos(x —2 sin(x) cos(x 2 sin(x) cos(x) provided cos(x) 0 2 cos(x) — sin(x) we conclude that cos(x — sin(x) as desired. Note: Using limits, we can show that this formula also holds for values of x for which cos(x) ................
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