n 7
B+2B/3 = 5B/3 = 90
base maggiore B = 90*3/5 = 54 cm
base minore b = 54*2/3 = 36 cm
AH = (B-b)/2 = 18/2 = 9 cm
lato obliquo l = √h^2+AH^2 = √256+81 = 18,36 m
perimetro 2p = 2l+b+B = 90+18,36*2 = 126,72 cm
area A = 90*16/2 = 720 cm^2
somma basi b+B = 2A/h = 628/12 = 54 cm = 2b+pr
pr = √lo^2-h^2 = √20^2-12^2 = 16 cm
base minore b = (54-pr)/2 = (54-16)/2 = 19 cm
base maggiore B = b+pr = 19+16 = 35 cm
perimetro 2p = 54+12+20 = 86 cm