The 120 degree triangle preserving matrix
we found in the previous section, can be transformed into four 60 degree triangle preserving matrices. To do so, we will need the following identity,
We have . Then using ,
where . However, from equation (40), . Hence
where is a 60 degree triangle. Similarly, if , then
where and .
Let
Then, clearly,
are also 60 degree triangle preserving matrices.
For example, since
,
where
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