Three Dot Products, One Norm

★ 7/10inequalityvectors

Problem

Plane vectors a⃗,b⃗,c⃗\vec a, \vec b, \vec c satisfy

a⃗⋅b⃗=1,b⃗⋅c⃗=1,c⃗⋅a⃗=2.\vec a \cdot \vec b = 1, \qquad \vec b \cdot \vec c = 1, \qquad \vec c \cdot \vec a = 2.

Find the range of ∣a⃗+b⃗+c⃗∣\left|\vec a + \vec b + \vec c\right|.

Answer

Solution

Difficulty7/10
Topicsinequality, vectors

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