6 replies to this topic

[-DC*3-Jp^Uk]

Hi guys, ok this is wierd, currently working my way through a math/physics book for game programmers and ive come across a question which even some of my friends who have done engineering degrees and are rock solid with maths (maths we call it over here in England :P )..but this problem is sooo annoying and i cant let it go until i figure out how the author has done this...the most annoying thing is that its basic maths, high school stuff, and their easy to do but this one is wierd anyway...

ok take a cartesian co - ordinate system, but not screen co - ordinates as Y goes up posittive.

The equation is Y = 3 and Solve X is the question. The author tells you to input a few numbers into the equation, here is it:

So Y = 3 is the same as the Ax + By = C form when you go - 0x + 1y = 3.

so...

1) x = -1.
2) x = 0.
3) x = 1.

So obviously the idea is to plug those value sinto the equation but then she gives the answers and they look like this...(p.s. if you where plotting this on a graph, which i am, then y will always = 3.)

1) (-4,3)
2) (0,3)
3) (4,3)

I can solve it for (4,3) but then the rest just dont add up at all.. :blink: I cant believe how I and many others have been made to feel thick by being stumped with this easy question... :blink: :blush:

Please guys hope you can help, which one will be the genious that does it ? :P

Thanks!

[baldurk]

I'm not sure what the problem is. If the equation is y = 3 then any co-ordinate with the y value 3 will fit that equation. (-4, 3) (0, 3) (4, 3) (58, 3) all lie on that line.

[anubis]

perhaps you need to reformulate your problem ? i don't see any probs at all either...

[coelurus]

Seems a bit unecessary to say, but would you mind copying an extract from that exercise and paste it here?

[robocop]

The problem really makes no sense. If u dont mind just write it down again .......only then can anyone help u

[MashRinx]

Okay, Basically a rehash of what baldurk was saying and I'm too many years out of geometry class, but if I remember right, Y=3, graphed, would be a straight, vertical line crossing the X-Axis at 3. If this is true, which I'm pretty sure it is), then regardless of what value you use for X, the Y coordinate should still be 3.

I think the confusion is coming from trying to plug the coordinates into the formula in the original post. I don't recall all the rules, but I don't think it is meant to be used in all cases??

Anyway, I hope this helps somewhat..

Mash

[-DC*3-Jp^Uk]

yes I understand now, I was trying to plug values in the orginal equation which was the mistake, tho i was lead into doing that! thnx for help m8! :D