Current location - Training Enrollment Network - Mathematics courses - 20 15 why does Zigong senior high school entrance examination mathematics set a straight line bc and an axis of symmetry x=
20 15 why does Zigong senior high school entrance examination mathematics set a straight line bc and an axis of symmetry x=
∫X = 1 is the symmetry axis of parabola,
∴OA=OB，
∴OA+OC minimum is OB+OC minimum,
When b, m and c are on the same straight line,
MB+MC=BC minimum.
When not in BC, MB+MC > BC (the shortest line segment between two points).