Triangle Midsegment

The MIDSEGMENT OF A TRIANGLE is a segment that connects the midpoints of and 2 of the triangle's sides.   In the applet below, be sure to change the locations of the triangle's vertices before sliding the slider.  Be sure to drag the slider several times.  As you do, pay close attention to the phenomena you're observing.   After interacting with the applet below for a few minutes, please answer the questions that follow.  
Questions:   1) What 2 facts does this applet illustrate about the midsegment of any triangle     with respect to the triangle's 3rd side?      2) Formally prove these 2 statements true using either the format of a 2-column proof,     coordinate geometry proof, or paragraph proof.