[SOLVED] Simple Transformation I have a simple reflection illustraded in matric form that should be presented in geometric form: // cos(5pi/6) sin(5pi/6) // // sin(5pi/6) -cos(5pi/6) // (this should look like 2*2 matrix; see the file "transformation.jpg" if you want to see it prettier) SOLUTION "This matrix represents a reflection in y = x*tan(5pi/12)". However, I do not understand why the angle is now 5pi/12 and not 5pi/6 as in the matrix. Moreover, what is the difference if the minus sign was in the front of the other cos( ) in the left hand corner and not in the right hand corner? How would the angle differ? Please, help me.