I must convert a isosceles trapezoid to a rectangle in 2-D with a shearing transformation (or with 2 shearing transformations).  The isosceles trapezoid is centered in the origin of axes.It is right write: x' = x + y y'=ywith >0  per y>0 ,  and <0  per y<0 (then 2 transformations)?And if it's right how can I calculate the parameter ?Otherwise if it is all wrong as I do?     
Transform a centered isosceles trapezoid in a rectangle in 2-D
transformations;computational geometry;geometry;maths;affine transformations