Question

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Answer 1

Letra A
$cos30^o=\frac{10}{x}\\ \frac{\sqrt3}{3}=\frac{10}{x}\\ x=\frac{30}{\sqrt3}.\frac{\sqrt3}{\sqrt3}\\ x=\frac{30\sqrt3}{3}\\ x=10\sqrt3$

Letra B
$\frac{\sqrt3}{2}=\frac{x}{8}\\ x=\frac{8\sqrt3}{2}\\ x=4\sqrt3$

Letra C
$\frac{\sqrt2}{2}=\frac{12}{x}\\ x=\frac{24}{\sqrt2}.\frac{\sqrt2}{\sqrt2}\\ x=\frac{24\sqrt2}{2}\\ x=12\sqrt2$

Letra D
$tg30\\ \frac{\sqrt3}{3}=\frac8x\\ x=\frac{24}{\sqrt3}.\frac{\sqrt3}{\sqrt3}\\ x=\frac{24\sqrt3}{3}\\ x=8\sqrt3$

Letra E
$sen45\\ \frac{\sqrt2}{2}=\frac{x}{40}\\ x=\frac{40\sqrt2}{2}\\ x=20\sqrt2$