theorem Lm20A: :: FUZZY_7:19

for a, b, c being Real
for f being Function of REAL,REAL st b > 0 & c > 0 & ( for x being Real holds f . x = max (0,(b - |.((b * (x - a)) / c).|)) ) holds
for x being Real st not x in ['(a - c),(a + c)'] holds
f . x = 0