∵z1+z2+z3=0∴cosα+cosβ+cosθ=0
sinα+sinβ+sinθ=0
∴cosα?+sinα?=(cosβ+cosθ)?+(sinβ+sinθ)?
cos(β-θ)=-?
β-θ=2kπ-π/3
同理可得:
θ-α=2nπ-π/3
两式相减得:α+β=2(k-n)π
所以cos(α+β)=1
∵z1+z2+z3=0∴cosα+cosβ+cosθ=0
sinα+sinβ+sinθ=0
∴cosα?+sinα?=(cosβ+cosθ)?+(sinβ+sinθ)?
cos(β-θ)=-?
β-θ=2kπ-π/3
同理可得:
θ-α=2nπ-π/3
两式相减得:α+β=2(k-n)π
所以cos(α+β)=1