perpendicular bisector

Go to the website to read the definition of a perpendicular bisector.

View this video to find how to measure sides and angles in geogebra.

Measure AD, DC, angles EDC and BCD in the construction below to determine if the blue line or the red line is the perpendicular bisector. Move the figure to see how measurement change.

Which line BD (blue) or DE (red) is the perpendicular bisector? Support your answer choice.