Given a set of 2D points and a rotation angle (in radians), build the corresponding 2x2 rotation matrix (its columns must be orthonormal and its determinant must be +1) and use it as a simple linear layer that rotates every input point. Return the rotated points as a list of [x, y] pairs.

Input:

• X: a list of 2D points, where each point is [x, y].
• angle: a float, the rotation angle in radians.

Output:

• A list of the rotated points, each as [x, y].