How to find the minimum value of an expression

Consider the diagram. which line segment has the same measure as st? rx tx sr xs

The graph shows the distance y, in inches, a pendulum moves to the right (positive displacement) and to the left (negative displacement), for a given number of seconds x. how many seconds are required for the pendulum to move from its resting position and return? enter your answer in the box.

What could explain what happened when the time was equal to 120 minutes