Answer:
CD = 4
Step-by-step explanation:
I believe you know the geometric mean for altitudes?
CD = √AD * DB = √8 * 2 = √16 = 4
If you are not aware of this theorem, then use the similarity of triangles.
ADC ~ CDB
AD/DC = CD/DB (cross-multiply)
CD^2 = AD*DB,
CD = √AD * DB = √8 * 2 = √16 = 4
