Question

Alguém para ajudar?

Answer 1

.
$AC=40km \\ AB=50km \\ \\ sen ~x= \frac{3}{4} \\ \\ sen~y= \frac{3}{7}$

A)
Lei dos senos

$\frac{BC}{sen~x} = \frac{AC}{sen~y} \\ \\ \frac{BC}{ \frac{3}{4} } = \frac{40}{ \frac{3}{7} } \\ \\ \frac{3}{7} .BC=40. \frac{3}{4} \\ \\ BC=30\div \frac{3}{7} \\ \\ BC=\not30^{10}\times \frac{7}{\not3} \\ \\\fbox{ BC=70 km }$

B)
$Como \\ \overline{DE}~//~\overline{BC} \\ \\ \triangle~~ADE~~\cong~~\triangle~~ABC \\ \\ logo \\ \\ \frac{AD}{AB} = \frac{DE}{BC} \\ \\ \frac{30}{50} = \frac{DE}{70} \\ \\ 50.DE=2100 \\ \\ DE=2100\div50 \\ \\\fbox{ DE=42KM }$