Question

Valor exato Sen(5π/8)cos(5π/8)​

Answer 1

Resposta:

sen(a+a)=2*sen(a)*cos(a)

Sen(5π/8)cos(5π/8)​ = (1/2)* sen(5π/8+5π/8)

Sen(5π/8)cos(5π/8)​ = (1/2)* sen(10π/8)

Sen(5π/8)cos(5π/8)​ = (1/2)* sen(5π/4)

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5π/4 =225º

sen(225)= sen(180+45 )=sen 180 * cos 45 +sen 45* cos 180

sen(225)=0*cos 45 -sen 45=-√2/2

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Sen(5π/8)cos(5π/8)​ = (1/2)*(-√2/2) =-√2/4