Question

$sin2arccos(-frac{12}{13})$

Answer 1

$sin(2arccos(-dfrac{12}{13}))=2sin(arccos(-dfrac{12}{13}))cos(arccos(-dfrac{12}{13} ))=\=-dfrac{24}{13}cdotsqrt{1-dfrac{144}{169}} =-dfrac{24}{13}cdot dfrac{5}{13} =-dfrac{120}{169}$