Rotating rectangle with collisions - c

Question

So currently im making a game in raylib library in C
I was expecting to rotate the rectangle but what really did happen the rectangle was being rotated using rectanglepro function but collision werent defined on it so it failed.
im using the following code but it doesnt work
RotatedVector = Vector2Rotate(Vector2Normalize(Center),angle*DEG2RAD);
Where as Vector2Rotate is function of raymath.h defined as:
RMAPI Vector2 Vector2Rotate(Vector2 v, float angle)
{
Vector2 result = { 0 };
float cosres = cosf(angle);
float sinres = sinf(angle);
result.x = v.x*cosres - v.y*sinres;
result.y = v.x*sinres + v.y*cosres;
return result;
}
Vector2Normalize is defined as
RMAPI Vector2 Vector2Normalize(Vector2 v)
{
Vector2 result = { 0 };
float length = sqrtf((v.x*v.x) + (v.y*v.y));
if (length > 0)
{
float ilength = 1.0f/length;
result.x = v.x*ilength;
result.y = v.y*ilength;
}
return result;
}