Answer:
AD = 10
Step-by-step explanation:
It's given that ABCE is a rectangle.
Therefore, measure of opposite sides of the rectangle will be equal.
AB = EC
AB = ED + DC
12 = ED + 4
ED = 8
Measure of side AE = 6
Since, measure of interior angles of a rectangle = 90°
Therefore, ΔEAD will be a right triangle.
By Pythagoras theorem,
AD² = AE² + ED²
= 6² + 8²
AD =
=
= 10
Therefore, measure of side AD = 10 units