Trigonometria

COS(α) = 4/5---> SIN(α) = √(1 - (4/5)^2) = 3/5

COS(β) = 3/5----> SIN(β) = √(1 - (3/5)^2) = 4/5

COS(2·α) = COS(α)^2 - SIN(α)^2

COS(2·α) = (4/5)^2 - (3/5)^2 = 7/25

SIN(2·α) = √(1 - (7/25)^2) = 24/25

Quindi:

SIN(γ) = SIN(pi - (2·α + β))----> SIN(γ) = SIN(2·α + β)

SIN(γ) = SIN(2·α)·COS(β) + SIN(β)·COS(2·α)

SIN(γ) = 24/25·(3/5) + 4/5·(7/25) = 4/5

COS(γ) = √(1 - (4/5)^2) = 3/5