trigonometry – Use trigonometric output expression for calculation in a next step

Can’t use output sin[p] since Sin[p] is expected.

As a result of D[x, u] D[x, u] + D[y, u] D[y, u] + D[z, u] D[z, u] I’ve got a Mathematica output like u²+v²cos[p]² + v²sin[p]². As you see, cos and sin are given in lowercase letters, and Mathematica can’t use the expression for further simplifications since Cos and Sin are expected. What can I do to get the expected solution u²+v²?