Пошаговое объяснение:

S = 40*13/2=260мм^2

S = 3,2*3/2=4,8см^2

S = (2 1/2*5 1/5)/2=6,5дм^2

S = (5/6*8/15)/2=2/9км^2

S = (0,3*5/6)/2=1/8м^2

S = (1,25*2,4)/2=1,5м^2

S = (1,4*1 3/7)/2=1дм^2