Final answer:
In the context of longitudinal and transverse waves, each stretched region in a longitudinal wave corresponds to a trough, and each compressed region corresponds to a peak in a transverse wave.
Step-by-step explanation:
The stretched regions in the waveform of a longitudinal wave correspond to the areas called rarefactions. Similarly, compressed regions in a longitudinal wave correspond to the areas of compressions. When comparing longitudinal waves to transverse waves, the compressions in a longitudinal wave are analogous to the peaks in a transverse wave, and the rarefactions are analogous to the troughs. So, in a transverse wave, the area directly below a peak or above a trough would be the equivalent of a compressed or stretched region, respectively, in a longitudinal wave.
In more detail, wavelength in a longitudinal wave refers to the distance between two consecutive compressions or rarefactions, analogous to the distance between two consecutive peaks or troughs in a transverse wave. Both types of waves demonstrate a periodic disturbance in a medium, but the orientation of the disturbance to the direction of wave propagation differs: it is parallel in longitudinal waves and perpendicular in transverse waves.