Angles (direction) in Vector Calculus

[TrueTears]

Not a specific question, but how exactly do you know when to use dot product and to find the angle between two vectors or

Or should it yield the same angle? And how do you know whether to subtract the answer from 90 degrees or 180?

Do we just need to try and visualise it?

Well the dot product gives the angle between 2 vectors when they are connected tail to tail and the angle is between 0 and 180 degrees.

Not sure what you mean with the tan(theta)... But yeah just visualise it

[darkphoenix]

The tan(theta)=y/x that thing.

[TrueTears]

it's not really related with the dot product though

you use the tan(theta) = y/x when you have a triangle and you have the length of the opposite side to the angle theta and also the adjacent and you need to work out theta.

[darkphoenix]

Yeah it is different. But in the book sometimes they use that method and other times they use dot product.

Thats why i was wondering

[chansthename]

LOL Essentials is soo hard though, so depressing when you cant do so many of the questions.

Maths Quest is insanely hard too, for a completely different reason, all the answers and questions are wrong (ok, slight exaggeration) and it is INFURIATING

[Andiio]

In easier questions, just try and visualise the shape and vectors added head to tail in your mind; a diagram would help. Normally for these types of 'easier' questions, you can just apply the tan(theta) y/x rule and then - or + according to whatever quadrant it is in. However the dot product is a more generic method for harder questions.

[darkphoenix]

^Ah alright cool

@chansthename, yeah far out, maths quest is so shit seriously lol wayy too many errors. and pages are so thin.