As shown in the figure, if point C is the midpoint of line AB, e and F are the midpoint of AC and BC respectively, ab = 12cm, find the length of EF Variant 1: if C is any point on the line AB, e and F are the midpoint of AC and BC respectively, ab = 12cm, then EF = -. Variant 2: if C is an extension point on the line AB, e and F are the midpoint of AC and BC respectively, ab = 12cm, then EF = -. Variant 3: if C is a reverse extension point on the line AB, e and F are the midpoint of AC and BC respectively, ab = 12cm, then EF = -. Variant 4: if C is any point on the line AB, e and F are AC respectively, If the midpoint of BC, ab = 12cm, then EF = - (draw the figure according to the situation and write out the complete process

As shown in the figure, if point C is the midpoint of line AB, e and F are the midpoint of AC and BC respectively, ab = 12cm, find the length of EF Variant 1: if C is any point on the line AB, e and F are the midpoint of AC and BC respectively, ab = 12cm, then EF = -. Variant 2: if C is an extension point on the line AB, e and F are the midpoint of AC and BC respectively, ab = 12cm, then EF = -. Variant 3: if C is a reverse extension point on the line AB, e and F are the midpoint of AC and BC respectively, ab = 12cm, then EF = -. Variant 4: if C is any point on the line AB, e and F are AC respectively, If the midpoint of BC, ab = 12cm, then EF = - (draw the figure according to the situation and write out the complete process

Variant 1: EF = 6cm from the figure, EF = EC + FC = AC / 2 + BC / 2 = (AC + BC) / 2 = AB / 2 = 6cm variant 2: & nbsp; EF = 6cm from the figure, EF = ec-fc = AC / 2-bc / 2 = (ac-bc) / 2 = (AB + bc-bc) / 2 = AB / 2 = 6cm Variant 3: EF = 6cm from the figure, EF = fc-ec = BC / 2-ac / 2 = (BC-AC) / 2 = (AB + AC-AC)