and are vertical. is the horizontal north-line through . is horizontal.
The distance AB = .
Suppose the height . Use the right-angled triangles to write down, in terms of and (and sines/cosines\tangents of various angles) the lengths of and . Then use the Sine Rule on the , and you're there.
For part 2, draw a horizontal line through to meet at . Therefore .
Then work out the distances and in terms of . Then use to get the result.
You can do it!