Question

Find the dot product, a • b.

a = 6i + 5j, b = -5i + 4j

50
<1, 9>
-10
<-30, 20>

Answer 1

multiply the corresponding components, then add up the products

Answer 2

what do you get when you do so?

Answer 3

i.i=j.j=k.k=1
1.j=j.k=k.i=0
as i.i=|i||i| cos 0=(1)(1)1=1
i.j=|i||j| cos 90=(1)(1) 0=0

Answer 4

i'm still confused