sin 50 + cos 50 = sin 50 + cos (90-40) = sin 50 + sin 40=2 sin 45 × cos 5 = 2 × √2/2 × cos 5 = √2 × cos 5
sin 50 + cos 50 = sin 50 + cos (90-40) = sin 50 + sin 40=2 sin 45 × cos 5 = 2 × √2/2 × cos 5 = √2 × cos 5