Final answer:
The adjacent side to angle x in a right triangle is the side that lies alongside angle x but is not the hypotenuse, and in the given context, is labeled 'x'.
Step-by-step explanation:
The adjacent side to an angle in a right triangle is the side that forms the angle with the hypotenuse of the triangle. Based on the information provided, which is reminiscent of concepts from vectors and trigonometry, if we consider angle x as the marked angle in a right triangle, the adjacent side would be the side that lies alongside angle x but is not the hypotenuse.
Using the last statement as a reference, in Figure 5.17, for a right triangle, the adjacent side, opposite side, or hypotenuse are defined in relation to a given angle. Specifically for angle x, the adjacent side is labeled as 'x' in the figure, the opposite side as 'y', and the hypotenuse as 'h'. So, the adjacent side to angle x is the side labeled 'x', which aligns with the x-axis direction as noted in other vector-related instructions in the provided information.