Bonsoir,
[tex]A=sin(\dfrac{\pi}{2}-x)+sin(\dfrac{\pi}{2}+x)+sin(x-\dfrac{\pi}{2})\\\\A=sin(\dfrac{\pi}{2}-x)+sin(\dfrac{\pi}{2}+x)-sin(\dfrac{\pi}{2}-x)\\\\A=sin(\dfrac{\pi}{2}+x)\\\\A=cos(x)[/tex]
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[tex]B=cos(\dfrac{\pi}{2}+x)+cos(\dfrac{3\pi}{2}+x)+cos(x-\dfrac{\pi}{2})\\\\B=cos(\dfrac{\pi}{2}+x)+cos(\dfrac{3\pi}{2}+x)+cos(\dfrac{\pi}{2}-x)\\\\B=-sin(x)+sin(x)+sin(x)\\\\B=sin(x)[/tex]
