This snippet of code works in one program but the Simplify fails when I cut and pasted it into another program.

Jac := Simplify[JacArray];
JacTrans := Transpose[Jac];
Met := Simplify[JacTrans.Jac];

JacArray is a Jacobian matrix and Met is the corresponding Metric. The value of Met when it fails in my test case is {cos[\[Theta]]^2 + sin[\[Theta]]^2, 0, 0, 0}, {0, r^2 (cos[\[Theta]]^2 + sin[\[Theta]]^2), 0, 0}

It doesnt recognize that cos[\[Theta]]^2 + sin[\[Theta]]^2 equals 1. FullSimplify doesnt help.

The main difference in the programs is that in the successful case I set Coordinates and query the system to get the Jacobian Matrix and in the unsuccessful case I put up a dialog that lets the user enter the Jacobian Matrix.