Math Is Fun Forum

Au101

Member

Registered: 2010-12-01

Posts: 353

Vectors practice

Hello again.

I've tried all sorts, I've looked at it every which way I know how, I was sure I'd be able to figure this one out, but - finally - I decided it was time to move on. So, what am I overlooking here?

So:

...And I run out of steam. Anything else I try to do from there always leads me back to a restatement of something I've already worked out. So I thought maybe it's not about simple vector arithmetic, maybe I have to try and use the fact that it's given me a ratio to work out some other ratios, but I've not been able to make any breakthroughs. At one point I tried constructing a rectangle around the whole shape with vertices O and A as well as one directly above O at the same height as B and D and another at that height and directly above A. Finally I tried resolving b and expressing it as some vertical component x + some fraction of a, but I couldn't make any of these approaches work.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,626

Re: Vectors practice

hi Au101

I'm with you right down to CD =

You also know that CD is parallel to OC so CD = j.OC for some scalar j.

Form two equations by equating the 'a' components and the 'b' components and solve for k.  (and j but you don't need this)

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Au101

Member

Registered: 2010-12-01

Posts: 353

Re: Vectors practice

Lovely stuff Thanks bob bundy!