Express Y coordiante

**BadMonkey** · April 10th 2010, 05:19 AM

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

**Grandad** · April 10th 2010, 05:47 AM

Hello BadMonkey

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

**BadMonkey** · April 10th 2010, 06:21 AM

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?

**Grandad** · April 10th 2010, 07:43 AM

Hello BadMonkey

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:

Originally Posted by BadMonkey

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

Grandad

Thread: Express Y coordiante