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As you practise many problems, you will learn to write the \(\sin\) and \(\cos\) terms automatically. One thing to remember is that whenever an inclined plane makes an angle \(\theta\) with the ground, the component of the weight along the plane is given by \(\sin \theta\). The component perpendicular to the plane is given by \(\cos \theta\). You then have to choose the \(+\) or the \(-\) sign, according to the coordinate system.
What about \(W_x\) and \(W_y\) here?
  • \(W_x = W \sin \theta, W_y = W \cos \theta\)
  • \(W_x = - W \sin \theta, W_y = W \cos \theta\)
  • \(W_x = W \sin \theta, W_y = - W \cos \theta\)
  • \(W_x = W \cos \theta, W_y = - W \sin \theta\)