The expression can be simplified as follows:

sin(-a) = -sin(a) (since sine is an odd function)
ctg(-a) = -cot(a) (since cotangent is an odd function)

Therefore, the expression becomes:
-sin(a) - sin(a)*(-cot(a))^2

To simplify further, we use the identity cot(a) = 1/tan(a):
-sin(a) - sin(a)(-1/tan(a))^2
= -sin(a) - sin(a)(-1)^2/tan(a)^2
= -sin(a) - sin(a)/tan(a)^2
= -sin(a) - cos(a)/sin(a)
= -sin(a) - cot(a)

So, Sin(-a)-sina*ctg^2(-a) simplifies to -sin(a) - cot(a).