Question

qual é o seno de 120°?

Answer 1

$\textrm{sen}(2x) = 2\, \textrm{sen}x \, \textrm{cos}x \\ \textrm{sen}120 = \textrm{sen}(2 \cdot 60) \\ = 2 \cdot \textrm{sen}60 \cdot \textrm{cos}60 \\ = 2 \cdot \frac{ \sqrt{3} }{2} \cdot \frac{1}{2} = \frac{ \sqrt{3} }{2} \\ \\ \textrm{sen}120 = \frac{ \sqrt{3} }{2}$