Perimeter, Area, and Volume Chapter question...?

ABC is a triangular paddock, with its measurements as shown: (diagram) A=Right angled, c=2km, a=3km.

What I need help on is part c) , I've done the rest as shown:
Find:

a) the perimeter of the paddock.
Pythagorean theorem, found side b (=2.24km) then added the sides up = 7.74 km
b) the area of the paddock in hectares
1/2*2*2.24= 2.24km^2
1km squared= 100 hectares
so 224 hectares
c)the shortest distance from A to the fence joining BC.  Hint: Use b)

How am I supposed to use the area to find the height of the new-formed right triangle?  I don't want to have to resort to using sin and cos rules as no mention of such use was needed in this chapter I'm studying.