Question

What is the projection of (4,4) onto (-7,3)?

Answer 1

Let's define the vectors:
 u = (4,4)
 v = (- 7.3)
 The projection of u on v is:
 P = ((u.v) / (v ^ 2)) v
 We have then:
 u.v = (4,4). (- 7.3)
 u.v = (4) * (- 7) + (4) * (3) = -28 + 12 = -16
 v ^ 2 = (- 7) ^ 2 + (3) ^ 2 = 49 + 9 = 58
 Substituting we have:
 P = ((- 16) / (58)) (- 7, 3)
 Rewriting:
 P = -0.28 (-7, 3)
 Answer:
 the projection of (4,4) onto (-7,3) is:
 C) -0.28 (-7.3)