goniometria potete aiutarmi

2·α + β = pi

(quadrilateri inscritti!!)

COS(α) = 1/4

SIN(α) = √(1 - (1/4)^2)---> SIN(α) = √15/4

SIN(2·α) = 2·SIN(α)·COS(α)

SIN(2·α) = 2·(√15/4)·(1/4)----> SIN(2·α) = √15/8

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

√15/8 = SIN(β)

√(1 - (√15/8)^2) = COS(β)

7/8 = COS(β)

TAN(β) = √15/8/(7/8)----> TAN(β) = √15/7