If cos4x - sin4x = \(\frac{3}{5}\), find 1 - 2sin2x + 2 sinx cosx is equal to:
Answer & explanation
Correct answer: option 2
⇒ cos4x - sin4x = \(\frac{3}{5}\)
⇒ (cos2x + sin2x) (cos2x - sin2x) = \(\frac{3}{5}\)
⇒ (cos2x - sin2x) = \(\frac{3}{5}\)
⇒ (cos 2x) = \(\frac{3}{5}\)
So,

⇒ (1 - 2sin2x) + (2 sinx cosx)
= (cos2x) + (sin2x)
= \(\frac{3}{5}\) + \(\frac{4}{5}\)
= \(\frac{7}{5}\)