Answer:
![\mathbf{DE=11}](https://img.qammunity.org/2020/formulas/mathematics/high-school/yl0wcpoa3iz679d38tfr5inrka5sp9idoe.png)
Explanation:
given AD = DB , means D is the midpoint of AB
given AE = EC , means E is the midpoint of AC
MID POINT THEOREM
In a triangle ABC, if D and E is the midpoint of side AB and AC respectively.
Then DE is parallel to BC and length of DE is half of length of BC.
![\mathbf{DE=(1)/(2)BC}](https://img.qammunity.org/2020/formulas/mathematics/high-school/1d6srx5mccmue42xtj1os6da0lpvjq3djg.png)
BC = 22 (given in the question)
![\mathrm{DE=(1)/(2)*22}](https://img.qammunity.org/2020/formulas/mathematics/high-school/3pfuvum6y6yraj9lf9p9ttje96kiomeq8w.png)
![\therefore\mathbf{DE=11}](https://img.qammunity.org/2020/formulas/mathematics/high-school/vin9of3c76ee6tn3vlv5fz0lrneygvk9a8.png)