Question

Use C to denote cos x, and express Cos(x+20,000pi)

Answer 1

`\bf 20000\pi \iff 10000\cdot 2\pi \implies cos(2\pi )=1\qquad 10000\cdot 1\implies 1 \\\\\\ sin(2\pi )=0\qquad \qquad 10000\cdot 0\implies 0\\\\ -----------------------------\\\\ cos({{ \alpha}} + {{ \beta}})= cos({{ \alpha}})cos({{ \beta}})- sin({{ \alpha}})sin({{ \beta}})\\\\ -----------------------------\\\\ cos(x+10000\pi )=cos(x)cos(10000\pi )-sin(x)sin(10000\pi ) \\\\\\ cos(x+10000\pi )=cos(x)\cdot 1-sin(x)\cdot 0 \\\\\\ cos(x+10000\pi )=cos(x)`