Practice: Norm of a Vector

Which of the following statements are true:
  1. There exist vectors such that u+v=u+v\|\vec{u}+\vec{v}\|=\|\vec{u}\|+\|\vec{v}\|
  2. If u=v\|\vec{u}\|=\|\vec{v}\| then u=v\vec{u}=\vec{v}
  3. u+v\|\vec{u}+\vec{v}\| is equal to uv\|\vec{u}-\vec{v}\| for every pair of vectors u\vec{u} and v\vec{v}
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