Question

Hi. For the cross product problem 1B, how do you get the minus sign for 4k when the 4j X i was positive? (i + 2j) × (2i − 3j) = i × i − 3i × j + 4j × i − 6j × j = 0 − 3k − 4k − 6 · 0

Answer 1

\( \hat j \times \hat i = - [\hat i \times \hat j ] = - \hat k \)

crossies are not commutative

if you look at my avatar, you can see how to remind yourself of this if stuck

Answer 2

Thanks so much!

Answer 3

mp