How Do You Calculate Normal Force on an Inclined Plane in a Moving System?

[tigor]

Homework Statement

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Given inclined plane with mass M. The angle of inclination is Alpha (from the horizontal plane).
The plane has no friction.
On the plane block with mass m.
The whole system is moving rightwards with acceleration A0.
Find the N normal between M and m.

Homework Equations

m*g*sin(Alpha) + m*A0*cos(Alpha)=m*Ax
N + m*A0*sin(Alpha) -m*g*cos(Alpha)=m*Ay

The Attempt at a Solution

In those equations i have 3 variables and only 2 equations.
The Ax and Ay are projections of acceleration of m on the axises.
The only thought that comes to mind is to add third equation as tangent proportion between the Ax / Ay=tan(Alpha)
But i have some doubts ...
Any suggestions

Thank you in advance.

 

[tigor]

Well, - i figured out the problem - the Ay is 0, since the block stays on the plane.