Trigonometry problem

[Guru]

Points (a,b) (c,d) and (e,f) are points on a map


I want to calculate the co-ordinates of point (a,b)

s1 and s2 are known length (about 3 miles)

Co-ordinates of (c,d) and (e,f) are known


All co-ordinates are in dd mm.mmm format which may make things slightly harder.

Can anyone devise a pair of simultaneous equations to find a and b?

I know roughly what the (a,b) are for my values of c,d,e,f,s1 and s2 because I've plotted them on a map