See Example 1.1 in the Maple Student Portal. In the column "Student Topics," the first question in the subsection "Constructing algebraic objects" is "How do I enter a piecewise expression or function?" A complete answer is given in Example 1.1. (Access to the Student Portal is detailed in Section A-1.)

If the last entry to the piecewise command is a rule without a condition, this rule is applied "elsewhere."

The symbols $\le$ and $\ge$ can be selected from the Common Symbols palette, or typed as <= and >=, respectively. In math mode, Maple will automatically change the two characters to a single symbol.