Express as a product: 1 - 4sin^2(a)

Answer 1

1-4sin^2(a) (use algebraic identity for difference of squares, a^2-b^2 = (a-b)(a+b) )

= (1-2sin(a))(1+2sin(a))

Answer 2

1 - 4sin²a = 1² - (2sina)² = (1 - 2sina)(1 + 2sina)