Answer:
= 5
Step-by-step explanation:
From the given diagram we are required to find the length of 
The given parameters are;
ΔABC and ΔCDA are congruent
The length of
= 5
The length of
= 7
The length of
= 4
From ΔABC ≅ ΔCDA, we have;
=
By reflexive property
∴
= 5 is either equal to
or 
However,
= 4, therefore,
≠ 
We can then have;
=
= 5.