# Question from Introductory Classical Mechanics by Morin

I understand if the system is to not move then the normal force from the ball to the triangle would have to support the weight of the triangle(or other shape depending on the problem). However, the solution calculates the horizontal component of the normal force. I thought the ball already applied some normal force onto the triangle due to gravity so wouldn’t the force you must apply be a little less than the horizontal component of the normal force? ($$Fn=Fa+Fg$$ so $$Fa except the solution says $$Fa=Fn$$.)