Answer:
see below
Step-by-step explanation:
Angle ACE = DCE since they are vertical angles
Angle A = Angle E parallel lines cut by a transversal form congruent alternate interior angles
Angle B = Angle D parallel lines cut by a transversal form congruent alternate interior angles
When all three angles are equal, the triangles are similar.
We can use ratios to find DE
DE CE
------- = ----------
AB AC
DE 8
------- = ----------
12 10
Using cross products
10 DE = 8*12
10 DE = 96
Divide by 10
DE = 9.6
