## Question 21 - Final question on higher paper

I cant think of a way to "show that y=....". Do I compare to x values?

Thx
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 Given coordinates of two points on the plane, how would you find the distance between them? Write down mathematically what the statement says and solve for y.
 Recognitions: Homework Help Just use the Distance Formula. This is the typical way of helping new students of Intermediate Algebra to understand parabolas. Your textbook probably also shows an example like the question which you asked.

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## Question 21 - Final question on higher paper

What IS the distance from a point (x,y) to (0, 2)?
What IS the distance from a point (x,y) to the x-axis?

Since the problem tells you that those two distances are the same write down those two formulas and set them equal.
 (x,y) - (x,0) = (x,y) -(0,2) is that right?
 Blog Entries: 1 Recognitions: Gold Member Science Advisor Staff Emeritus Does this ring any bells; $$d = \sqrt{\left(x_1-x_0\right)^2+\left(y_1-y_0\right)^2}$$

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 Quote by thomas49th (x,y) - (x,0) = (x,y) -(0,2) is that right?
I don't even know what that means!

I know how to subtract numbers.
I even know how to subtract vectors.

How do you subtract points?
 LHS x - x = 0 y - 0 = y RHS x - 0 = x y - 2 = y - 2 SO y = x + y - 2 x = 2 that right?

 Quote by thomas49th LHS x - x = 0 y - 0 = y RHS x - 0 = x y - 2 = y - 2 SO y = x + y - 2 x = 2 that right?
Nooo!

Take a look at Hootenanny's post.
 ive never ever seen that formula in my life, and I think it is beyond GCSE level (that exams you do in UK when your 15 or 16). Is that formula the simplest way?

 Quote by thomas49th ive never ever seen that formula in my life, and I think it is beyond GCSE level (that exams you do in UK when your 15 or 16). Is that formula the simplest way?
I thought most people would have seen that formula at least a couple of years before they turn 16!

Given any two points (x0,y0) and (x1,y1), the distance between them is given by that formula. It's just the Pythagorean theorem done on the Cartesian plane. In three dimensions, there would also be the (z1-z0)2 within the square root.

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 Quote by thomas49th ive never ever seen that formula in my life, and I think it is beyond GCSE level (that exams you do in UK when your 15 or 16). Is that formula the simplest way?
Is it not just Pythagoras' Theorem in a different guise?
 how would cristo go about solving it then?

 Quote by cristo Is it not just Pythagoras' Theorem in a different guise?
It is. You're right.
 is it just me or are the quotes note displaying today?
 Rhythmer, if your posts are being deleted it is because you have not read the forum guidelines! Answering questions for people is not the purpose in the homework forums; The idea is to get them to do at least a significant portion of the work on their own, so that they can actually learn to understand the material. Guidelines: http://physicsforums.com/showthread.php?t=94379

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 Quote by Rhythmer Well, I've already experienced some moderators deleting my posts in this section on which I answer homework questions, but I think I'm allowed to answer this one simply because it's not homework.
As data mentions above, any and all questions which are coursework/homework type questions (regardless of whether the homework is set to be handed in) must be answered in a tutorial type way. That means, waiting for the original poster to show some work before giving help, and providing hints or suggestions as opposed to complete solutions.

 how would cristo go about solving it then?
Well, cristo would follow Halls' hint, using Hootenanny's formula for the distance, and then set them equal.