Formula ariei:
[tex]\boldsymbol{ \mathcal{A}_{\Delta } = \dfrac{\ell_{1} \cdot \ell_{2} \cdot \sin \alpha}{2}}[/tex]
unde α = ∡(l₁, l₂)
[tex]a) \mathcal{A}_{\Delta } = \dfrac{5 \cdot 8 \cdot \sin 30^{\circ}}{2} =20 \cdot \dfrac{1}{2} = 10 \ cm^2[/tex]
[tex]b) \mathcal{A}_{\Delta } = \dfrac{6 \cdot 4\sqrt{3} \cdot \sin 60^{\circ}}{2} = 12\sqrt{3} \cdot \dfrac{\sqrt{3} }{2} = 18 \ cm^2[/tex]
[tex]c) \mathcal{A}_{\Delta } = \dfrac{8 \cdot 12 \cdot \sin 45^{\circ}}{2} = 48 \cdot \dfrac{\sqrt{2} }{2} = 24\sqrt{2} \ cm^2[/tex]
