prove that every line segment has one and only one mid point by using euclid's postulates and axioms.
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Let there be 2 midpoints C and D of line AB
When C is MP, AC =BC ---- eqn 1
When D is MP, AD = BD ---- eqn2
Subtract eqn 1 frm 2
AD - AC = BD - BC
CD= -CD (writing DC as -CD means the same)
CD + CD = 0
2CD = 0
CD = 0
This is possible only when C coincides with D
Hence there is only 1 midpoint.