y′=5cos(x)y' = 5\cos \left( x \right)y′=5cos(x), decreciente en (0,π2)\left( {0,{\pi \over 2}} \right)(0,2π), (3π2,5π2)\left( {{{3\pi } \over 2},{{5\pi } \over 2}} \right)(23π,25π) y (7π2,12)\left( {{{7\pi } \over 2},12} \right)(27π,12)