/ /x y\ /pi*x\\ lim |sin|- - -|*tan|----|| x->y+\ \2 2/ \2*y //
Limit(sin(x/2 - y/2)*tan((pi*x)/((2*y))), x, y)
/ /x y\ /pi*x\\ lim |sin|- - -|*tan|----|| x->y+\ \2 2/ \2*y //
-y --- pi
/ /x y\ /pi*x\\ lim |sin|- - -|*tan|----|| x->y-\ \2 2/ \2*y //
-y --- pi
-y/pi