Answer:
DE = 4 units.
Step-by-step explanation:
By the chord intersection theorem:
BE * CE = DE * FE
But FE = DE + 5 so:
BE * CE = DE * (DE + 5)
6 * 6 = DE^2 + 5DE
DE^2 + 5DE - 36 = 0
(DE + 9)(DE - 4) = 0
So DE = -9 or 4
It can't be negative so DE = 4.
