tính sin^2.10°- sin^2.20°+sin2^2.30° -sin2^40° -sin^2.50 °-sin^2.50°+sin^2.60°-sin^2.70°+sin^2.80° 12/07/2021 Bởi Hadley tính sin^2.10°- sin^2.20°+sin2^2.30° -sin2^40° -sin^2.50 °-sin^2.50°+sin^2.60°-sin^2.70°+sin^2.80°
$\sin^210^o+\sin^280^o-(\sin^220^o+\sin^270^o)+\sin^230^o+\sin^260^o-(\sin^240^o+\sin^250^o)$ $=\sin^210^o+\cos^210^o-(\sin^220^o+\cos^220^o)+\sin^230^o+\cos^230^o-(\sin^240^o+\cos^250^o)$ $=1-1+1-1=0$ Bình luận
$\sin^210^o+\sin^280^o-(\sin^220^o+\sin^270^o)+\sin^230^o+\sin^260^o-(\sin^240^o+\sin^250^o)$
$=\sin^210^o+\cos^210^o-(\sin^220^o+\cos^220^o)+\sin^230^o+\cos^230^o-(\sin^240^o+\cos^250^o)$
$=1-1+1-1=0$