In a line segment, segment AC = segment BD. Fill in the reasons to prove segment CD is congruent to segment AB.
1.Segment AC = segment BD 1._____ I think this would be "given"
2. AC= AB +BC 2.__ (I think this is segment addition postulate)
3. AB+BC=BD 3.__ (I think this is segment addition postulate)
4. BD=BC+CD 4._(I think this is substitution property of equality)
5. AB+BC=BC+CD 5._ (I think this is addition property of equality)
6. AB = CD 6._ (I think this is subtraction property of equality)
7.CD=AB 7. (I think this is symmetric property of equality)
8.CD is congruent to AB 8. (I think this would be definition of congruent segments)
Thank you for your help.
1 Answer | Add Yours
Line segments are congruent if they have the same length.
Draw a straight line AD. Take two points B and C in between A and D such that points A, B, C, and D appear in a sequence, say from left.
Given segment AC = segment BD ---- (i)
Again, Splitting AC and BD in terms of further segments, we can write
AC = AB + BC and similarly, BD = BC + CD
Therefore, applying addition property in equality (i) it follows that,
AB + BC = BC + CD
`rArr` AB = CD (subtracting the common part BC from both sides)
Thus, option 5) should be the reason for congruence of AB and CD.
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