Answer:
1. 4cm
2. 14cm
Step-by-step explanation:
<h3>Similarity</h3>
Two shapes are similar if and only if the ratio of their corresponding sides are equal. That is, the ratio of their bases is equal to the ratio of their heights is equal to the ratio of their hypotenuses.
<h3>Congruence</h3>
If two shapes are said to be congruent, that means they are exacrly the same:same shape <u>and</u> same size
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If ΔPQR and ΔXYZ are similar,

If ABCD and DEFG are congruent,
AB=EF=CD=DG and BC=ED=AD=FG.
We have AB=CD=7 and AD=DE=21.
CE=DE-CD=21-7=14cm