The triangle ABC ∠ABC = 90°, AB ∶ BD ∶ DC = 3 ∶ 1 ∶ 3. If AC = 20 cm, then what is the length of AD (in cm)?

The triangle ABC ∠ABC = 90°, AB ∶ BD ∶ DC = 3 ∶ 1 ∶ 3.

1.	The triangle ABC ∠ABC = 90°, AB ∶ BD ∶ DC = 3 ∶ 1 ∶ 3. If AC = 20 cm, then what is the length of AD (in cm)?
A.	4√5
B.	5√2
C.	4√10
D.	6√3
Answer» D. 6√3