= 1 + sin^2a + 1 + sin^2a - 4sin^2a= 2 + 2sin^2a - 4sin^2a= 2 - 2sin^2a
Therefore, the final simplified expression is 2 - 2sin^2a.
= 1 + sin^2a + 1 + sin^2a - 4sin^2a
= 2 + 2sin^2a - 4sin^2a
= 2 - 2sin^2a
Therefore, the final simplified expression is 2 - 2sin^2a.