Question

18v35cos(2arcsin1/6)

Answer 1

$18 \sqrt{35} \cos(2\arcsin \frac{1}{6} )=18 \sqrt{35}(1-2\sin^2(\arcsin\frac{1}{6}))=\\ \\ \\ =18 \sqrt{35} (1-2\cdot (\frac{1}{6})^2)=18 \sqrt{35}- \sqrt{35} =17 \sqrt{35}$