Question

найти 3cosx, если sinx=-2√2/3

Answer 1

$sinx= frac{-2 sqrt{2} }{3} \ cosx= sqrt{1^{2}- sin^{2} x} = sqrt{1- ( frac{-2 sqrt{2} }{3}) ^{2} } = sqrt{1- frac{8}{9} }= sqrt{ frac{1}{9} }= frac{1}{3} \ 3cosx=3* frac{1}{3}=1$