acos²θ+asin²θ=? Is ACOS & # 178; θ + bsin & # 178; θ =?
acos²θ+asin²θ
=a(cos²θ+sin²θ)
=a
It is proved that 4sin α cos α (COS & # 178; α - Sin & # 178; α) = SiN4 α=
Left = 4sin α cos α (COS & # 178; α - Sin & # 178; α) = 2sin2a · cos2a = SiN4 α