Answer:

Step-by-step explanation:
Given

Required
Find 
From the attachment:
The measure of
is calculated using the following expression:

Where
-- right-angled.
The expression becomes



Paying off a debt over time with planned payments, so kind of like mortgage on a house.
Answer:
DC = 3
Step-by-step explanation:
Based on triangle similarity theorem, we would have the following equation:

Plug in the values



Cross multiply
3(9 + DC) = 9×4
27 + 3DC = 36
Subtract 27 from each side
3DC = 36 - 27
3DC = 9
Divide both sides by 3
DC = 9/3
DC = 3