looks like I am doing everything manually.
i will find the suface that is on a slope for right angled triangle 3d Shape (the longest side).
now the slope is at a 45 deg angle .
4 points around this rectangle surface is
A(0,0,0)
B(200,0,0)
C(200,71,71)
D(0,71,71)
V1 vector1= B - A (200,0,0)
V2 vector2=C - A (200,71,71)
cross product vector1 X vector2
cross product x= v1.y X v2.z - v1.zX v2.y = 0X71 - 71X0= 0
cross product y= - (( v2.z X v1.x) - (v2.x X v1.z)) = - 71X200 -0= -14200
cross product z= v1.x X v2.y - v1.y X v2.x= 14200
(0,-14200,14200) is normal so normalize i get
20081 = normalize factor
(0, -.707, .707) = normal vector for this shape
now since y value is negative the normal points down but i want it to point up dont I out of the surface?