a) . Sin^2 10° + Sin^2 20° + Sin^2 30° + Sin^2 40° + Sin^2 50° + Sin^2 60° + Sin^2 70° + Sin^2 80°
b) . Cos^2 25 ^2 + Cos35° + Cos^2 55° + Cos^2 65°
Loga
Sinh Học lớp 12
