Корень из 50 cos 2 3п/8 минус корень из 50 sin 2 3п/8

√50(cos²(3π/8)) - √50(sin²(3π/8)) = √50(cos²(3π/8) - sin²(3π/8)) = √50(cos(2 × (3π/8))) = 5√2(cos(3π/4)) = 5√2 × (-√2/2) = -(5 × 2)/2 = -5