where s=(a+b+c+d)/2.
Heron's formula for the area of a triangle is the special case obtained by taking d=0.
... Stewart[?], (United Kingdom) 1972 - Jean-Pierre Beltoise[?], (France) 1973 - Jackie Stewart[?], (United Kingdom) 1974 - Ronnie Peterson[?], (Sweden) 1975 - Niki ...