Question

va rog , punctul a cu teorema lu heron va rog frumos si punctul b cum se rezolva el normal​

Answer 1

Explicație pas cu pas:

a)

$p = \dfrac{AB + AC + BC}{2} = \dfrac{5 + 5 + 8}{2} = \dfrac{18}{2} = 9 \ cm$

$\mathcal {A} = \sqrt{9(9 - 8)(9 - 5)(9 - 5)} = \sqrt{9 \cdot 1 \cdot 4 \cdot 4} = \\ = \sqrt{144} = \sqrt{ {12}^{2} } = \bf 12 \ {cm}^{2}$

b)

$\mathcal {A} = \dfrac{BE \cdot AC}{2} = \dfrac{CF \cdot AB}{2} \\ \dfrac{BE \cdot 5}{2} = \dfrac{CF \cdot 5}{2} = 12 \\ \dfrac{BE \cdot 5}{2} = 12 \implies BE = \dfrac{24}{5} \\ \dfrac{CF \cdot 5}{2} = 12 \implies CF = \dfrac{24}{5}$

$BE + CF = \dfrac{24}{5} + \dfrac{24}{5} = \dfrac{48}{5} = \bf 9.6 \: cm$