In the triangle ABC, AB * BC = 3, the area s of triangle ABC ∈ [root 3,3 / 2], then the value range of the angle between AB and BC

S = 0.5 * AB * bcsin α (α is the angle between AB and BC)
=1.5sinα
∵ s ∈ [root 3,3 / 2]
5 sin α ∈ [root 3,3 / 2]
Ψ sin α ∈ [2 radical 3 / 3,1]
α ∈ [arc2 radical 3 / 3, π / 2]

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