Calculation: HK5NIX - 1

AB  = 
saknis( (x2-x1)^2+ (y2-y1)^2)
AB = saknis( (x2-x1)^2+ (y2-y1)^2)$$AB$$ = $$\sqrt {(x2-x1)^{2}+(y2-y1)^{2}}$$