cos^2 x - sin^2 x если cosx=0.25

cos^2 x, если tanx=12

sin^2=1-cos^2cos^2x-sin^2x=2cos^2x-1=2*0.0625-1=-0.875cos^2+sin^2=1tg^2+1=1/cos^2cos^2=1/(tg^2+1)cos^2x=1/(tg^2x+1)=1/(144+1)=1/145