sin x − cos x = a, (π/4) ≤ x ≤ (π/2)
Which statement is correct?
(1) sin^2 x − cos^2 x = −(1/2)(√(3 + 2a^2 − a^4 ))
(2) sin^4 x + cos^4 x = (1/8)(−3a^4 + 6a^2 + 5)
(3) sin 2x = ((1 − a^2 )/2)
(4) tan^2 x + cot^2 x = ((−3a^4 − 2a^2 + 8a + 13 )/(2(a^4 + 2a^2 + 1)))
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