theorem Th4: :: FUZZY_9:11

for a, b, c being Real st a < b & b < c holds
(TriangularFS (a,b,c)) | [.a,c.] = ((AffineMap ((1 / (b - a)),(- (a / (b - a))))) | [.a,b.]) +* ((AffineMap ((- (1 / (c - b))),(c / (c - b)))) | [.b,c.])