Practice: Norm of a Vector

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