Question

Determine if the following vectors are parallel, perpindicular or neither.

1. {4,5} and {-4,-5}

Answer 1

oops

Answer 2

Yes to parallel do you mean?

Answer 3

{-4,-5} = -1 {4,5} so yes, they are parellel

Answer 4

So if they're equal they're parallel. How do I determine perpendicular?

Answer 5

if they have a 90 degree angle when u join them together

Answer 6

have you learnt about dot product?

Answer 7

So for (4,-10) and (6,-15) for example.

Answer 8

Yes I do but understand it rather vaguely.

Answer 9

okay well

Answer 10

Vector1 Dot Vector2 = Magnitudeof Vector1 * Magnitude of Vector2 * cos(anglebetweenthem)

Answer 11

when the angle between them =90 degrees
Then cos of 90 degrees = 0
so V1 dot V2 = 0
when they are perpendicular

Answer 12

http://tutorial.math.lamar.edu/Classes/CalcII/DotProduct.aspx
scroll down if you are interested in a proof of the dot product