化简sin(2π-α)×sin(π⼀2+α)×cos(-5π⼀2+α)⼀sin(3π-α)×cos(3π⼀2+α)

2024-12-25 17:57:20
推荐回答(2个)
回答1:

答案是-cosA

回答2:

sin(2π-α)=-sina
sin(π/2+α)=cosa
cos(-5π/2+α)=cos(5π/2-a)=cos(2π+π/2-a)=cos(π/2-a)=sina
sin(3π-α)=sin(2π+π-a)=sin(π-a)=sina
cos(3π/2+α)=cos(π+π/2+a)=-cos(π/2+a)=-[-sina]=sina
原式=-sinacosasina/(sinasina)
=-cosa