Explicație pas cu pas:
Aria triunghiului echilateral:
[tex] \frac{l {}^{2} \sqrt{3} }{4} [/tex]
a)
[tex]10= \frac{l {}^{2} \sqrt{3} }{4} \\ l {}^{2} \sqrt{3} = 40 \\ l {}^{2} = \frac{40}{ \sqrt{3} } \\ l = \frac{ \sqrt{40} }{ \sqrt[2]{3} } = \frac{2 \sqrt{10} }{ \sqrt[2]{3} } [/tex]
b)
[tex]15 = \frac{l {}^{2} \sqrt{3} }{4} \\ l {}^{2} \sqrt{3} = 60 \\ l {}^{2} = \frac{60}{ \sqrt{3} } \\ l = \frac{ \sqrt{60} }{ \sqrt[2]{3} } = \frac{2 \sqrt{15} }{ \sqrt[2]{3} } [/tex]