Maths Hl Mock P2 Q

Gangsta

Hi does anyone know how to do Q2 c) on paper 2? I've no idea which mock it is but heres the question anyway:

z= -i + 5j. Two vectors x and y are such that |x|=|y|=√13.
ox and oy make angles of 45degrees with oz, where o is the origin.

i) Find x and y in terms of i and j
ii) show that oxzy is a square.

I'd say I could figure out part ii) but all help is welcome!thanks!

Crumbs

Vectors x and y will be of the form ai + bj.
We know their moduli, so we can write sqrt(a^2 + b^2) = sqrt(13)

Now we use the given angle information to make a second equation:
x.z / |x|.|z| = cos 45º

Work that out and substitute into the first equation.
You should end up with two values for a and b, which gives you vectors x and y.

Part (ii) should be doable then but let me know if you've any problems or need any clarifications.

KnifeWRENCH

i got that mock too.... Q.2 was the hardest vectors question id ever seen!!! i only got 13/50 :eek:

md99

square_igloo wrote:

i got that mock too.... Q.2 was the hardest vectors question id ever seen!!! i only got 13/50 :eek:

Yep, horrible vectors Q... How could my beloved vectors turn on me?

Tomlowe

it raped me too... and the line question on orthocentres.... there was blood everywhere. i am not looking forward to getting that result back...

md99

Is it me, or do maths pre papers always seem to miss the mark by a mile? Ive done a few and I never do well in them, going by the past papers I can usually pull 30-40/50, in a lot of the pre paper Qs I'm lucky to get 20.... very frustrating!