Which Vector Proofs do we actually need to know?

[jto1292]

You could just prove that the diagonals are same length AND at a 90 degree angle. Or that the shape has 2 adjacent right angles and the lengths of perpendicular sides are same.

[Elnino_Gerrard]

So Diagonals at 90 degrees and then find their maginitudes and if their equal its  a square yes? or do i still have to prove adjacent sides equal?

[jto1292]

no further proof necessary after diagonals at 90 and their magnitude is same.

[Elnino_Gerrard]

Man im so confused ...in the the vcenotes guide for shapes it says for a parellelogram opposite sides are parellel. Yet in the vcaa 08 they say opposite sides are equal?

[jto1292]

 equal in magnitude (length), and parallel. They're both. I think..

[jasoN-]

i don't want to create another thread but question:
when doing dynamics and resolving forces can i write this:
resolving // to plane: __________
resolving _|_ (perpendicular symbol) to plane: ______

[jto1292]

i don't want to create another thread but question:
when doing dynamics and resolving forces can i write this:
resolving // to plane: __________
resolving _|_ (perpendicular symbol) to plane: ______

I don't see why not... Isn't that how you normally resolve forces?

[jasoN-]

just making sure // is recognisable as parallel
sometimes i see people draw in a small j versus i graph, indicating perpendicul and parallel axis and then go resolving in the 'i' direction etc.
i don't like this method

[98.40_for_sure]

Yeah i either do
equating forces // to plane ... equating forces |_ to plane (i colour in the little right angle thingie)
or
equating forces vert to plane ... equating forces horiz to plane

[jto1292]

Yea, I always put perp and para symbols when resolving. I don't think it's wrong..