# co ordinate geometry

• November 25th 2008, 12:30 PM
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, 12:39 PM
skeeter
(slope of AB)(slope of BC) = -1
• November 25th 2008, 12:43 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, 01:02 PM
In a right triangle $a^2 + b^2 = c^2$.
So $(b-2)^2 +(3-1)^2 + (b-5)^2 + (3-5)^2 = (5-2)^2 + (5-1)^2$