What is the <strong>MAXIMUM</strong> value of 1+2\sin^{2}\theta\cos^{2}\theta-\sin^{4}\theta-\cos^{4}\theta where 0^{\circ}\lt\theta\lt90^{\circ}?

  1. A. 1
  2. B. 2
  3. C. 3
  4. D. 4

Correct Answer: A. 1

Explanation

The expression can be rewritten as 1 - (\sin^4\theta - 2\sin^2\theta\cos^2\theta + \cos^4\theta) = 1 - (\sin^2\theta - \cos^2\theta)^2 = 1 - \cos^2 2\theta = \sin^2 2\theta. The maximum value of \sin^2 2\theta is 1, which occurs at \theta = 45^{\circ}.

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