Answer:
x = 3
Step-by-step explanation:
You want the equation of vertical line BD that includes point B(3, 2).
The equation of a vertical line is ...
x = c . . . . . . for some constant c
Since we want the line to go through a point B(3, 2) with x-coordinate 3, that is the value the constant must have.
x = 3 . . . . . the equation of line BD
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Additional comment
Ordinarily, this rectangle would be named ABDC, with the vertices named in order around the figure.