The minimum value of 3sin2 θ + 4cos2 θ is?

3 2 1 0

3

3sin2 θ + 4cos2 θ ⇒ 3sin2 θ + 3cos2 θ + cos2 θ ⇒ 3 + cos2 θ since cos2 θ > 0 ; minimum value occurs when cos2 θ = 0 ∴ minimum value = 3