Question

In Question 4, point C is called a mid-point of line segment AB. Prove that every line segment has one and only one mid-pointa

Answer 1

Let there be two such mid points C and D. Then from above theorem 

AC = 1 /2 AB 

and AD = 1 /2 AB 

∴ AC = AD 

But this is possible only if D coincides with C. Therefore, C is the unique mid-point. Proved.