Question

A altura de um triângulo isósceles cuja base mede 16 cm e cujos lados côngruos medem 17 cm é: a) 10 cm b) 12 cm c) 13 cm d) 14 cm e) 15 cm

Answer 1

17²=(16/2)²+x²
289=64+x²
x²=289-64
x²=225
x=√225
x=15

Answer 2

$Sabemos\ que:\\\\ b=16\ cm\ \ \| \ \ a=17\ cm\\\\ Calculando\ a\ altura:\\\\ h=\sqrt{a^2-\frac{b^2}{4}}\ \to\ h=\sqrt{17^2-\frac{16^2}{4}}\\\\ h=\sqrt{289-\frac{256}{4}}\ \to\ h=\sqrt{289-64}\\\\ h=\sqrt{225}\ \to\ h=15\ cm\\\\ Calculando\ a\ \acute area:\\\\ A=\frac{b.h}{2}\ \to\ A=\frac{16.15}{2}\\\\ A=\frac{240}{2}\ \to\ \| \ A=120\ cm^2\ \|$