teorema er-sinus y er-cosinus

teoremes:
cos[n:n](x^{n}) = (1/n)·( sin(x^{n})/x^{n} )


sin[n:n](x^{n}) = (1/n)·(1/x^{n})·( 1+(-1)·cos(x^{n}) )


demostracions:
d_{x}[ ∫ [0-->x^{n}][ cos(x) ] d[x] ] = cos(x^{n})·nx^{(n+(-1))}


d_{x}[ ∫ [0-->x^{n}][ sin(x) ] d[x] ] = sin(x^{n})·nx^{(n+(-1))}