Question

вычислите cosa, tga, cos2a если sina=-3/5 и 3п/2<a<2п

Answer 1

cosa=(1-sin^2(a))^0.5=(1-925)^0.5=45

Answer 2

tga=sinacosa=-35:(-45)=34

Answer 3

cos2a=cos^2(a)-sin^2(a)=725

Answer 4

спасибо