Question

Найдите 24$cos2 alpha$ , если $sin alpha =-0,2$.

Answer 1

cos^2x=1-sin^2x
sin^2x=0.04
cos^2x=1-0.04=0.92
cos2альфа=cos^2x-sin^2x
cos2альфа=0.92-0.04=0.88