An 18-foot board is leaning against a wall. It is set 6 feet from the base of the wall. How far up the wall does the board reach?

a vertical translation only

Step-by-step explanation:

Transformation is the movement of a point from its original position to its new position. In an object is to be transformed then all the points of the object are also transformed. Transformation can either be a reflection, rotation, dilation or translation.

Translation is the movement of the points of an object at the same direction and by the same distance. If the object is moved left or right then it is horizontally transformed but if it is moved up or down then it is vertically transformed. Since  triangle A B C is shifted 5 units up to form triangle A'B'C', this means that only a vertical translation is done.