Calculate the probability of seeing a landmark when starting at a given point and walking straight in a random direction Input 5 integers: Landmark X &amp; Y, Starting Point X &amp; Y, and View Distance Radius D

Output 1 double: % chance of coming within D of Landmark (X,Y) ("seeing") when walking straight in a random direction from Starting Point (X,Y).

Assume that "random direction" shall be a direction uniform on [0,2π], the land is flat, and of course the 'hiker' never turns after he begins moving.

Example: If landmark is at (10,10), starting point is (5,5), and view distance is 20 then the output would be 100% as no matter which direction you walk the landmark will be immediately visible.
Haskell, 65 63

import Data.Complex
(s,l)%d=100*min(asin(d/magnitude(s-l))/pi)1


Use like (xstart:+ystart, xlandmark:+ylandmark) % distance.  Gives result in percent.  Why is it so expensive to load modules in Haskell?!?

Note that there is no if/then/else, pattern matching, etc. in this code, min does the magic.