α⊥β ⟺ ∠(α,β)=90∘\alpha \perp \beta \iff \angle(\alpha, \beta)=90^{\circ}α⊥β⟺∠(α,β)=90∘.
α⊥β, a=α∩β, b⊂α, b⊥a ⟹ b⊥β\alpha\perp \beta,~a=\alpha\cap \beta,~b\subset \alpha,~b\perp a \implies b\perp \betaα⊥β, a=α∩β, b⊂α, b⊥a⟹b⊥β.
α⊥β ⟸ a⊂α, a⊥β\alpha\perp\beta \impliedby a\subset \alpha,~a\perp \betaα⊥β⟸a⊂α, a⊥β.
Last updated 7 days ago