utilizzando teorema area triangolo
area=1/2×lato×lato×seno angolo compreso
SIN(pi/3) = √3/2 = SIN(α)
SIN(β) =SIN(pi - pi/3 - γ) = SIN(γ + pi/3) =
SIN(γ)·COS(pi/3) + SIN(pi/3)·COS(γ) = √3·COS(γ)/2 + SIN(γ)/2
SIN(γ) = 3/5------> COS(γ) = √(1 - (3/5)^2) ----> COS(γ) = 4/5
Quindi:
SIN(β) =√3·(4/5)/2 + (3/5)/2 = 2·√3/5 + 3/10
Α = 1/2·a·c·SIN(β)
Α =1/2·20·8·√3·(2·√3/5 + 3/10) = 24·√3 + 96 = 24·(√3 + 4)