Question

sin a/2=8/17; п<а<2п; найти cos a и tg a​

Answer 1

$sinfrac{a}{2} = frac{8}{17} => cosfrac{a}{2} = -sqrt{1 - (frac{8}{17})^2} = -frac{15}{17} \cosa = cos^2frac{a}{2} - sin^2frac{a}{2} = frac{161}{289}\ tan(a) = sqrt{frac{1}{cos^2(a)} - 1 } = sqrt{frac{289^2}{161^2} - 1} = sqrt{frac{450*128}{161^2} } = frac{240}{161}$