# Express Y coordiante

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• April 10th 2010, 05:19 AM
BadMonkey
Express Y coordiante
Hello
Help with the question on my drawing please?
its a rectangle in isoceles right triangle
• April 10th 2010, 05:47 AM
Grandad
Hello BadMonkey
Quote:

Originally Posted by BadMonkey
Hello
Help with the question on my drawing please?
its a rectangle in isoceles right triangle

If the triangles are isosceles and right-angled, then B is the point $(0,1)$. So the equation of AB is
$x+y=1$
So, making $y$ the subject:
$y = 1-x$
which gives the value of $y$ at the point P.

Grandad
• April 10th 2010, 06:21 AM
BadMonkey
Thanks
I got that but I was no sure if it was correct

but I done it this way y-y1=m(x-x1)
1-x=0(1-x)
would it be correct to write it like this also?
• April 10th 2010, 07:43 AM
Grandad
Hello BadMonkey
Quote:

Originally Posted by BadMonkey
Thanks
I got that but I was no sure if it was correct

but I done it this way y-y1=m(x-x1)

You can certainly use
$y-y_1=m(x-x_1)$
to get the equation of the line. Using
$x_1=1,\;y_1=0$ and $m = -1$
gives
$y-0=-1(x-1)$

$\Rightarrow y = 1-x$
But this line doesn't make sense, and is not correct:
Quote:

Originally Posted by BadMonkey
1-x=0(1-x)
would it be correct to write it like this also?

Grandad