Concept:Use the identities cos2x−sin2x=cos2x and 1−sin2x=cos2x to simplify the fraction.Explanation:Start with 1−sin2xcos2x−sin2x.Replace 1−sin2x with cos2x.The expression becomes cos2xcos2x−sin2x.Separate the numerator: cos2xcos2x−cos2xsin2x.Simplify each term: 1−tan2x.Answer:C. 1−tan2x