1. Midpoint and Median
P9. The midpoint of the hypotenuse of a right triangle is equidistant from the 3 vertices.
P12. The length of a leg of a right triangle is the geometric mean between the length of its projection on the hypotenuse and the length of the hypotenuse. A M C B

2. Median – line segment from a vertex to the midpoint of the opposite sideC B
Altitude – line segment from a vertex that intersects the opposite side at a right angle. A H C B

3. Three elements at play in defining median, perpendicular bisector and altitude.
It is drawn from the vertex
It is drawn to the midpoint of the opposite side
It is perpendicular to the opposite side
MEDIAN
ALTITUDE
Perpendicular Bisector
Drawn from Vertex
Drawn to Midpoint of opposite side
Perpendicular to opposite side 

4. MEDIAN Altitude Drawn from Vertex Drawn to Midpoint of opposite side
Perpendicular to opposite side
MEDIAN
Altitude
Perpendicular bisector