The $\alpha$ angle is supposed to be 90.00 degrees. Couldn't get it right with the graph tool!
I'm trying to understand why the CK segment isn't
$$ CK = CJ*cos(Y) \\ CK = CJ*\frac{CA}{CB} $$
and the correct answer is (using similar triangles relationships):
$$ \frac{CA}{CJ} = \frac{CB}{CK} \\ CK = CJ*\frac{CB}{CA} $$
equivalent to
$$ CK = CJ*\frac{1}{cos(Y)} $$