Given: Trigonometric Expression is sin4θ+cos4θ−2sin2θcos2θ Concept Used: −1≤cosθ≤1,0≤cos2θ≤1 −1≤sinθ≤1,0≤sin2θ≤1 cos2θ−sin2θ=cos2θ Calculation: We have sin4θ+cos4θ−2sin2θcos2θ ⇒(cos2θ)2+(sin2θ)2−2⋅sin2θ⋅cos2θ Using formula a2+b2−2ab=(a−b)2 ⇒(cos2θ−sin2θ)2 ⇒(cos2θ)2 ⇒cos22θ According to the concept used The minimum value of cosθ is 0 ∴ The minimum value of cos22θ is 0 .