Answer:
The answer to your question is CD = 4
Explanation:
Data
AD = 8
BD = 2
CD = ?
Process
Use proportions to solve this problem. Compare triangle ACD and triangle CDB.
Large triangle CD/AD
Small triangle BD/CD
Equal both proportions
CD/BD = AD/CD
-Solve for CD
CD² = AD x BD
-Substitution
CD² = 8 x 2
-Simplification
CD² = 16
-Result
CD = 4