Basic getForward cos sin Question

Scripting Issues
1

Let’s say I’ve got:

node.getQuat().getForward()

and

sin(deg2Rad(node.getH())),  -cos(deg2Rad(node.getH())), 0

where node is a Nodepath. The command returns:

Vec3(0.866025, -0.5, 0)
-0.866025403784 0.5 0

I wonder why it is not exactly the same but rather the former is the latter by -1 and vice versa?