# SOLUTION: If D is the midpoint of line AC and C is the midpoint of line AB, and AD is 3 cm., what is the length of AB?

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 Question 153973: If D is the midpoint of line AC and C is the midpoint of line AB, and AD is 3 cm., what is the length of AB?Answer by Edwin McCravy(8912)   (Show Source): You can put this solution on YOUR website!If D is the midpoint of line AC and C is the midpoint of line AB, and AD is 3 cm., what is the length of AB? ``` Draw AC @-----------@ A C >>...D is the midpoint of line AC...<< So put D in the middle of AC @-----@-----@ A D C >>...C is the midpoint of line AB...<< So Extend AC twice its length to B so that C will be in the middle of AB @-----@-----@-----------@ A D C B >>...AD is 3...<< So put 3 on AD 3 @-----@-----@-----------@ A D C B Put another 3 on DC, because DC is the same length as AD. 3 3 @-----@-----@-----------@ A D C B That makes AC have length 3+3 or 6. Since CB is the same length as AC, we write 6 on CB 3 3 6 @-----@-----@-----------@ A D C B Add up the pieces AB = AD + DC + CB = 3 + 3 + 6 = 12. Edwin```