Unit Vector Notation (part 2)

[ladymarmalade1710]

I have a question regarding unit vectors. My teacher told me that unit vectors only represent the positive direction of an axis. If this is true, then why can we draw -3i in the negative direction? How does -3i even exist if the unit vector only applies to the positive direction of the axis? Any help would be appreciated. Thanks!

[ppenna]

@ladymarmalade1710 The unit vectors are positive to start. Example: i = 1 in the x direction unit, j=1 in the y direction. So by definition yes it is positive, but when you multiply i by a negative number it goes the opposite direction of i. Just like when you multiply any positive number by a negative number. -4i is just saying the vector's direction and magnitude on the x axis is going to the point (-4, 0).

[SpasticWire]

thanks (i got it already though)

[SpasticWire]

How do you get the direction of the resultant vector using the unit vector notation??

[dlwodnd]

@SpasticWire because its been 2 months so i dont know if you are still interested in the answer

but you use the trigonometry to figure out the direction.

For instance, from the example in the video, when the vectors of the resultant was -1i + 6j

the "opposite" side is 6 and "adjacent" side is 1

using inverse tangent, the angle is 80.5 degrees from the negative x-axis

hope this helped if you havent figured this out already :)

[superbigpony]

hairy balls

[123456sag]

all good words in dictionery

[lawrencewong100]

now i can pass my quiz tomorrow without payin attention in class~ hahaha xDD

[madscirat]

School - grading curves - standardized testing - uninterested students -uninspired teachers = learning. Thanks Sal.

[ose90]

excellent! Prepare to get A's in my pre-u test now :)

[iBGalaxy]

I understand vectors now!!!!!!!!!!!!!

[xlwaiyiplx]

not confusing at all, easier to understand than the textbook

[ZZanacasandraZZ]

We actually wen on the algebraic method without knowing the concept of adding vectors! But now its clear how we got that method

[rishabhgpt3]

bakwas.......

[ZZanacasandraZZ]

lol it wasnt tat much bakwas also!

[santoshonline]

No. This is the real learning. 5*

[pasa69]

Very good :) 5*

[disneypassholder]

I'm embarrassed at how simple it is, and how confusing I found my linear algebra text. I'm very disappointed in the author, and delighted to have found your explanation.

[sheeps83]

Yea that was brilliant, explained very well. thanks sal

[ReaverKS]

It wasn't confusing, you did a very good job of explaining, 5 out of 5