y‌‌=4sin2θ−cos‌2‌θ ‌‌=4sin2θ−(1−2sin2θ) ‌y=6sin2θ−1 ∵‌‌0≤sin2θ≤1 ⇒‌‌0≤6sin2θ≤6 ⇒‌‌−1≤6sin2θ−1≤5‌‌‌ or ‌‌‌−1≤y≤5 Maximum value of y=5⇒m=5 Minimum. value of y=−1⇒l=−1 ‌lm=−5,‌