cos(α+π⼀3)=1⼀4,则cos(2α+2π⼀3)

2025-03-13 05:31:47
推荐回答(1个)
回答1:

cos(α+π/3)=1/4,
cos(2α+2π/3)
=cos[2(α+π/3)]
=2cos²(α+π/3)-1
=2*(1/4)²-1
=-7/8