the equation of the plane is
. To determine the coefficients
let
be the value of
for one of the four known points
. For example,
is the
value for the point
Then set
,
and
For the fifth point
,
Since 3 points determine a plane, the fourth known point should satisfy
The equation of a plane is
. To determine the coefficients
let
be the value of
for one of the four known points
. For example,
is the
value for the point
Now let
denote the fifth point. Take the first triangle to be (0,0), (64,0) and (0,64). The fifth point is in this triangle if
Then set
,
and
For the fifth point,
The second triangle is (64,64), (64,0) and (0,64). The fifth point is in this triangle if
Then set
,
and
For the fifth point,