Question

18 sin40 Х Cos 40___________________ Sin 80

Answer 1

$\frac{18sin 40cos 40}{sin 80}=\\ \frac{9*2sin 40cos 40}{sin 80}=\\ \frac{9*sin(2*40)}{sin 80}=\\ \frac{9*sin(80)}{sin 80}=9$