1. The problem statement, all variables and given/known data The block resting on the inclined plane shown has a mass of 40kg. Determine the maximum and minimum value of P for which the block is in equilibrium. (fs=0.35 and θ=25°) The image on top is the diagram in the book and the image below it is my free-body diagram (not too sure if the Fr (friction) force is correct though) 3. Attempt at the solution Now my problem isn't exactly but how to solve this, since I found the solution online. My question is more about the trigonometry used to find some of the forces in this diagram. I found that the w (the weight) is of course (40)(9.8) = 392.4. Now the question is this: The solution and the book claims that N=(392.4)(cos 25) = 355.64. However I am confused because if I say that: cos 25 = a/h (N) cos 25 = 392.4/h h=392.4/cos 25 = 432.97 Which is incorrect. Can some explain why in my mind, I am 100% that this equation does indeed solve for the hypotenuse, yet the book claims that it is the product of the two? Is my free-body diagram wrong? I am certain i that it isn't (except maybe the friction force which may be wrong). Once I understand this I am sure I can better understand the solution to this problem and other similar problems.