Question

11cos2a если cosa=0.6

Answer 1

$11cos2 alpha = 11(cos^2 alpha -sin^2 alpha ) \ cos^2 alpha =0.6^2=0.36 \ sin^2 alpha =1-cos^2 alpha = 1-0.36=0.64 \ 11(cos^2 alpha-sin^2 alpha ) =11(0.36-0.64) = -3.08$
ИЛИ
$11cos2 alpha =11(2cos^2 alpha -1) \ cos^2 alpha =0.6^2=0.36 \ 11(2cos^2 alpha -1)=11(2*0.36-1) = 11(0.72-1) = -3.08$