Explanation:
Mid Point : A point which lies on the line segment and is equidistant from both the ends of the segment is called a mid point.
A line segment can have ONLY ONE mid point and it divides the line segment into two equal parts.
Now, Given : C is the midpoint of AB.
and B is the midpoint of CD.
⇒ AC = BC and BC = BD
Now by Euclid's Lemma
- "Things which are equal to the same thing are equal to each other."
Here, AC = BC , and BC = BD
⇒ AC = BD
Hence the result.