Tg(2 arccos 12/13)= помогите,пожалуйста !!!!срочно!!!!

Tg(2 arccos 12/13)=
$tg(2arccos( \frac{12}{13}))= \frac{sin(2arccos( \frac{12}{13})) }{cos(2arccos( \frac{12}{13})) }=$

$=\frac{2sin(2arccos( \frac{12}{13}))*cos(arccos( \frac{12}{13}) }{2cos^2(arccos( \frac{12}{13})-1}=$

$=\frac{2 \sqrt{1-cos^2(arccos( \frac{12}{13}))}*\frac{12}{13}}{2*\frac{12^2}{13^2}-1}=\frac{\frac{24}{13}\sqrt{1-\frac{12^2}{13^2}}}{\frac{288}{169}-1}=\frac{\frac{24}{13}\sqrt{\frac{169-144}{169}}}{\frac{288-169}{169}}=\frac{\frac{24}{13}\sqrt{\frac{25}{169}}}{\frac{119}{169}}=$

$=\frac{\frac{24}{13}*\frac{5}{13}}{\frac{119}{169}}= \frac{120}{119}$