Final answer:
To evaluate the expression, we simplify the numerator and denominator separately using trigonometric identities.
Step-by-step explanation:
To evaluate the expression given, we'll start by simplifying the expression in the numerator and denominator separately.
In the numerator, we have 1 - 2*cos^2(a/2). We can use the identity cos^2(x) = 1 - sin^2(x) to rewrite this as 1 - 2*(1 - sin^2(a/2)). Simplifying further, we get 1 - 2 + 2*sin^2(a/2) = -1 + 2*sin^2(a/2).
In the denominator, we have 2 - sin^2(a). We can combine these terms as 2 - 1 + cos^2(a) = 1 + cos^2(a).
So, the expression evaluates to (-1 + 2*sin^2(a/2))/(1 + cos^2(a)).