Add a force at an angle

How do I add a force at specific angle to an object? Currently I am trying to do the following:

rigidbody2D.AddForce(new Vector2(1,Mathf.Cos(angle))*force);

where angle would represent the angle at which the force is added, so if i wanted a force straight up then angle would be 90. However this does not seem to work, and I would like to know what the correct way to accomplish this is.
I am using C# and unity 2D

How about this:

 Vector3 dir = Quaternion.AngleAxis(angle, Vector3.forward) * Vector3.right;
 rigidbody2D.AddForce(dir*force);

The angle starts on the right and goes counter-clockwise.