Which pair of vectors is perpendicular?

Question

A. <4,1> , <-8, 1>

 

B. <5,0>, <-3,2>

 

C. <5, -3>, <2,3>

 

D. <-9, -3>, <2 - 6>

 

Answer 1

Let's do a dot product for each choice:

 

A: ⟨4,1⟩·⟨-8,1⟩ = -32 + 1 = -31 ≠ 0

B: ⟨5,0⟩·⟨-3,2⟩ = -15 + 0 = -15 ≠ 0

C: ⟨5,-3⟩·⟨2,3⟩ = 10 - 9 = 1 ≠ 0

D: ⟨-9,-3⟩·⟨2,-6⟩ = -18 + 18 = 0

 

So it's choice D.