# co ordinate geometry

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• November 25th 2008, 01:30 PM
adeshSB
co ordinate geometry
can anyone help??
got this question,,
The points ABC have co ordinates (2, 1) (b,3) and (5,5) where b>3
and angle ABC=90degrees ??
I know the answer just have no idea how to work it out.
• November 25th 2008, 01:39 PM
skeeter
(slope of AB)(slope of BC) = -1
• November 25th 2008, 01:43 PM
Plato
In a right triangle $a^2 + b^2 = c^2$.
So $(b-2)^2 +(3-1)^2 + (b-5)^2 + (3-5)^2 = (5-2)^2 + (5-1)^2$
• November 25th 2008, 02:02 PM
adeshSB
does that make b= 6
cause i justtried and got some strange answer sorry i'm a bit rubbish at this
Quote:

Originally Posted by Plato
In a right triangle $a^2 + b^2 = c^2$.
So $(b-2)^2 +(3-1)^2 + (b-5)^2 + (3-5)^2 = (5-2)^2 + (5-1)^2$