C - va Acos((w2 w₁)t/2)cos(w2 + w₁)t/2) xb Asin((w2 w₁)t/2) sin(w2+ w₁)t/2) E₁ = 1/2mA²(w2 + w₁)/2)² cos²((w2w₁)t/2) E₁ = 1/2mA²(w2+ w₁)/2)²sin² ((w2 w₁)t/2)