[问答题]
Consider the graphs nhq1 prqf9) +lwl)99zv abv+mof- z6x rfjm tscja20ed8 d)s.qlo)g-e* $y=-\frac{1}{2}|x|$ and y=2|x|-a , where $a \in \mathbb{Z}^{+}$ .
1. Sketch the graphs on the same set of axes.
2. Given that the graphs enclose a region of area 40 square units, find the value of a .
