| amplitude | Half the difference between the maximum and the minimum values of a periodic function. |
| cycle | Any part of a graph of a periodic function that is one period long. |
| period | The length of the smallest interval that contains exactly one copy of the repeating pattern of a periodic function. |
| periodic function | A function whose graph has a pattern that repeats forever in both directions. |
| reflection | A mirror-image of a graph. If the reflection is over the x-axis, then the part of the original graph that was below the x-axis will be above the x-axis, and vice versa. |