Question

mă poate ajuta cineva va rog ......​

Answer 1

$\cos(30) = \frac{ac}{bc} \\ \cos(c) = \frac{ac}{12} \\ \frac{ \sqrt{3} }{2} = \frac{ac}{12} \\ ac = \frac{12 \sqrt{2} }{2} = 6 \sqrt{2}$